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  <div class="section" id="api">
<span id="id1"></span><h1>API<a class="headerlink" href="#api" title="Permalink to this headline">¶</a></h1>
<span class="target" id="module-flask"></span><p>This part of the documentation covers all the interfaces of Flask.  For
parts where Flask depends on external libraries, we document the most
important right here and provide links to the canonical documentation.</p>
<div class="section" id="application-object">
<h2>Application Object<a class="headerlink" href="#application-object" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="flask.Flask">
<em class="property">class </em><tt class="descclassname">flask.</tt><tt class="descname">Flask</tt><big>(</big><em>import_name</em>, <em>static_path=None</em>, <em>static_url_path=None</em>, <em>static_folder='static'</em>, <em>template_folder='templates'</em>, <em>instance_path=None</em>, <em>instance_relative_config=False</em><big>)</big><a class="headerlink" href="#flask.Flask" title="Permalink to this definition">¶</a></dt>
<dd><p>The flask object implements a WSGI application and acts as the central
object.  It is passed the name of the module or package of the
application.  Once it is created it will act as a central registry for
the view functions, the URL rules, template configuration and much more.</p>
<p>The name of the package is used to resolve resources from inside the
package or the folder the module is contained in depending on if the
package parameter resolves to an actual python package (a folder with
an <cite>__init__.py</cite> file inside) or a standard module (just a <cite>.py</cite> file).</p>
<p>For more information about resource loading, see <a class="reference internal" href="#flask.Flask.open_resource" title="flask.Flask.open_resource"><tt class="xref py py-func docutils literal"><span class="pre">open_resource()</span></tt></a>.</p>
<p>Usually you create a <a class="reference internal" href="#flask.Flask" title="flask.Flask"><tt class="xref py py-class docutils literal"><span class="pre">Flask</span></tt></a> instance in your main module or
in the <cite>__init__.py</cite> file of your package like this:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">flask</span> <span class="kn">import</span> <span class="n">Flask</span>
<span class="n">app</span> <span class="o">=</span> <span class="n">Flask</span><span class="p">(</span><span class="n">__name__</span><span class="p">)</span>
</pre></div>
</div>
<div class="admonition-about-the-first-parameter admonition ">
<p class="first admonition-title">About the First Parameter</p>
<p>The idea of the first parameter is to give Flask an idea what
belongs to your application.  This name is used to find resources
on the file system, can be used by extensions to improve debugging
information and a lot more.</p>
<p>So it&#8217;s important what you provide there.  If you are using a single
module, <cite>__name__</cite> is always the correct value.  If you however are
using a package, it&#8217;s usually recommended to hardcode the name of
your package there.</p>
<p>For example if your application is defined in <cite>yourapplication/app.py</cite>
you should create it with one of the two versions below:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">app</span> <span class="o">=</span> <span class="n">Flask</span><span class="p">(</span><span class="s">&#39;yourapplication&#39;</span><span class="p">)</span>
<span class="n">app</span> <span class="o">=</span> <span class="n">Flask</span><span class="p">(</span><span class="n">__name__</span><span class="o">.</span><span class="n">split</span><span class="p">(</span><span class="s">&#39;.&#39;</span><span class="p">)[</span><span class="mi">0</span><span class="p">])</span>
</pre></div>
</div>
<p class="last">Why is that?  The application will work even with <cite>__name__</cite>, thanks
to how resources are looked up.  However it will make debugging more
painful.  Certain extensions can make assumptions based on the
import name of your application.  For example the Flask-SQLAlchemy
extension will look for the code in your application that triggered
an SQL query in debug mode.  If the import name is not properly set
up, that debugging information is lost.  (For example it would only
pick up SQL queries in <cite>yourapplication.app</cite> and not
<cite>yourapplication.views.frontend</cite>)</p>
</div>
<p class="versionadded">
<span class="versionmodified">New in version 0.7: </span>The <cite>static_url_path</cite>, <cite>static_folder</cite>, and <cite>template_folder</cite>
parameters were added.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.8: </span>The <cite>instance_path</cite> and <cite>instance_relative_config</cite> parameters were
added.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>import_name</strong> &#8211; the name of the application package</li>
<li><strong>static_url_path</strong> &#8211; can be used to specify a different path for the
static files on the web.  Defaults to the name
of the <cite>static_folder</cite> folder.</li>
<li><strong>static_folder</strong> &#8211; the folder with static files that should be served
at <cite>static_url_path</cite>.  Defaults to the <tt class="docutils literal"><span class="pre">'static'</span></tt>
folder in the root path of the application.</li>
<li><strong>template_folder</strong> &#8211; the folder that contains the templates that should
be used by the application.  Defaults to
<tt class="docutils literal"><span class="pre">'templates'</span></tt> folder in the root path of the
application.</li>
<li><strong>instance_path</strong> &#8211; An alternative instance path for the application.
By default the folder <tt class="docutils literal"><span class="pre">'instance'</span></tt> next to the
package or module is assumed to be the instance
path.</li>
<li><strong>instance_relative_config</strong> &#8211; if set to <cite>True</cite> relative filenames
for loading the config are assumed to
be relative to the instance path instead
of the application root.</li>
</ul>
</td>
</tr>
</tbody>
</table>
<dl class="method">
<dt id="flask.Flask.add_url_rule">
<tt class="descname">add_url_rule</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.Flask.add_url_rule" title="Permalink to this definition">¶</a></dt>
<dd><p>Connects a URL rule.  Works exactly like the <a class="reference internal" href="#flask.Flask.route" title="flask.Flask.route"><tt class="xref py py-meth docutils literal"><span class="pre">route()</span></tt></a>
decorator.  If a view_func is provided it will be registered with the
endpoint.</p>
<p>Basically this example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="nd">@app.route</span><span class="p">(</span><span class="s">&#39;/&#39;</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">index</span><span class="p">():</span>
    <span class="k">pass</span>
</pre></div>
</div>
<p>Is equivalent to the following:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">def</span> <span class="nf">index</span><span class="p">():</span>
    <span class="k">pass</span>
<span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span><span class="s">&#39;/&#39;</span><span class="p">,</span> <span class="s">&#39;index&#39;</span><span class="p">,</span> <span class="n">index</span><span class="p">)</span>
</pre></div>
</div>
<p>If the view_func is not provided you will need to connect the endpoint
to a view function like so:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">app</span><span class="o">.</span><span class="n">view_functions</span><span class="p">[</span><span class="s">&#39;index&#39;</span><span class="p">]</span> <span class="o">=</span> <span class="n">index</span>
</pre></div>
</div>
<p>Internally <a class="reference internal" href="#flask.Flask.route" title="flask.Flask.route"><tt class="xref py py-meth docutils literal"><span class="pre">route()</span></tt></a> invokes <a class="reference internal" href="#flask.Flask.add_url_rule" title="flask.Flask.add_url_rule"><tt class="xref py py-meth docutils literal"><span class="pre">add_url_rule()</span></tt></a> so if you want
to customize the behavior via subclassing you only need to change
this method.</p>
<p>For more information refer to <a class="reference internal" href="#url-route-registrations"><em>URL Route Registrations</em></a>.</p>
<p class="versionchanged">
<span class="versionmodified">Changed in version 0.2: </span><cite>view_func</cite> parameter added.</p>
<p class="versionchanged">
<span class="versionmodified">Changed in version 0.6: </span><cite>OPTIONS</cite> is added automatically as method.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>rule</strong> &#8211; the URL rule as string</li>
<li><strong>endpoint</strong> &#8211; the endpoint for the registered URL rule.  Flask
itself assumes the name of the view function as
endpoint</li>
<li><strong>view_func</strong> &#8211; the function to call when serving a request to the
provided endpoint</li>
<li><strong>options</strong> &#8211; the options to be forwarded to the underlying
<a class="reference external" href="http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Rule" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">Rule</span></tt></a> object.  A change
to Werkzeug is handling of method options.  methods
is a list of methods this rule should be limited
to (<cite>GET</cite>, <cite>POST</cite> etc.).  By default a rule
just listens for <cite>GET</cite> (and implicitly <cite>HEAD</cite>).
Starting with Flask 0.6, <cite>OPTIONS</cite> is implicitly
added and handled by the standard request handling.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.after_request">
<tt class="descname">after_request</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.Flask.after_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Register a function to be run after each request.  Your function
must take one parameter, a <a class="reference internal" href="#flask.Flask.response_class" title="flask.Flask.response_class"><tt class="xref py py-attr docutils literal"><span class="pre">response_class</span></tt></a> object and return
a new response object or the same (see <a class="reference internal" href="#flask.Flask.process_response" title="flask.Flask.process_response"><tt class="xref py py-meth docutils literal"><span class="pre">process_response()</span></tt></a>).</p>
<p>As of Flask 0.7 this function might not be executed at the end of the
request in case an unhandled exception ocurred.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.after_request_funcs">
<tt class="descname">after_request_funcs</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.after_request_funcs" title="Permalink to this definition">¶</a></dt>
<dd><p>A dictionary with lists of functions that should be called after
each request.  The key of the dictionary is the name of the blueprint
this function is active for, <cite>None</cite> for all requests.  This can for
example be used to open database connections or getting hold of the
currently logged in user.  To register a function here, use the
<a class="reference internal" href="#flask.Flask.after_request" title="flask.Flask.after_request"><tt class="xref py py-meth docutils literal"><span class="pre">after_request()</span></tt></a> decorator.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.auto_find_instance_path">
<tt class="descname">auto_find_instance_path</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.Flask.auto_find_instance_path" title="Permalink to this definition">¶</a></dt>
<dd><p>Tries to locate the instance path if it was not provided to the
constructor of the application class.  It will basically calculate
the path to a folder named <tt class="docutils literal"><span class="pre">instance</span></tt> next to your main file or
the package.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.before_first_request">
<tt class="descname">before_first_request</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.Flask.before_first_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Registers a function to be run before the first request to this
instance of the application.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.before_first_request_funcs">
<tt class="descname">before_first_request_funcs</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.before_first_request_funcs" title="Permalink to this definition">¶</a></dt>
<dd><p>A lists of functions that should be called at the beginning of the
first request to this instance.  To register a function here, use
the <a class="reference internal" href="#flask.Flask.before_first_request" title="flask.Flask.before_first_request"><tt class="xref py py-meth docutils literal"><span class="pre">before_first_request()</span></tt></a> decorator.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.before_request">
<tt class="descname">before_request</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.Flask.before_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Registers a function to run before each request.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.before_request_funcs">
<tt class="descname">before_request_funcs</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.before_request_funcs" title="Permalink to this definition">¶</a></dt>
<dd><p>A dictionary with lists of functions that should be called at the
beginning of the request.  The key of the dictionary is the name of
the blueprint this function is active for, <cite>None</cite> for all requests.
This can for example be used to open database connections or
getting hold of the currently logged in user.  To register a
function here, use the <a class="reference internal" href="#flask.Flask.before_request" title="flask.Flask.before_request"><tt class="xref py py-meth docutils literal"><span class="pre">before_request()</span></tt></a> decorator.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.blueprints">
<tt class="descname">blueprints</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.blueprints" title="Permalink to this definition">¶</a></dt>
<dd><p>all the attached blueprints in a directory by name.  Blueprints
can be attached multiple times so this dictionary does not tell
you how often they got attached.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.config">
<tt class="descname">config</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.config" title="Permalink to this definition">¶</a></dt>
<dd><p>The configuration dictionary as <a class="reference internal" href="#flask.Config" title="flask.Config"><tt class="xref py py-class docutils literal"><span class="pre">Config</span></tt></a>.  This behaves
exactly like a regular dictionary but supports additional methods
to load a config from files.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.context_processor">
<tt class="descname">context_processor</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.Flask.context_processor" title="Permalink to this definition">¶</a></dt>
<dd><p>Registers a template context processor function.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.create_global_jinja_loader">
<tt class="descname">create_global_jinja_loader</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.Flask.create_global_jinja_loader" title="Permalink to this definition">¶</a></dt>
<dd><p>Creates the loader for the Jinja2 environment.  Can be used to
override just the loader and keeping the rest unchanged.  It&#8217;s
discouraged to override this function.  Instead one should override
the <a class="reference internal" href="#flask.Flask.jinja_loader" title="flask.Flask.jinja_loader"><tt class="xref py py-meth docutils literal"><span class="pre">jinja_loader()</span></tt></a> function instead.</p>
<p>The global loader dispatches between the loaders of the application
and the individual blueprints.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.create_jinja_environment">
<tt class="descname">create_jinja_environment</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.Flask.create_jinja_environment" title="Permalink to this definition">¶</a></dt>
<dd><p>Creates the Jinja2 environment based on <a class="reference internal" href="#flask.Flask.jinja_options" title="flask.Flask.jinja_options"><tt class="xref py py-attr docutils literal"><span class="pre">jinja_options</span></tt></a>
and <a class="reference internal" href="#flask.Flask.select_jinja_autoescape" title="flask.Flask.select_jinja_autoescape"><tt class="xref py py-meth docutils literal"><span class="pre">select_jinja_autoescape()</span></tt></a>.  Since 0.7 this also adds
the Jinja2 globals and filters after initialization.  Override
this function to customize the behavior.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.5.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.create_url_adapter">
<tt class="descname">create_url_adapter</tt><big>(</big><em>request</em><big>)</big><a class="headerlink" href="#flask.Flask.create_url_adapter" title="Permalink to this definition">¶</a></dt>
<dd><p>Creates a URL adapter for the given request.  The URL adapter
is created at a point where the request context is not yet set up
so the request is passed explicitly.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.6.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.debug">
<tt class="descname">debug</tt><a class="headerlink" href="#flask.Flask.debug" title="Permalink to this definition">¶</a></dt>
<dd><p>The debug flag.  Set this to <cite>True</cite> to enable debugging of the
application.  In debug mode the debugger will kick in when an unhandled
exception ocurrs and the integrated server will automatically reload
the application if changes in the code are detected.</p>
<p>This attribute can also be configured from the config with the <cite>DEBUG</cite>
configuration key.  Defaults to <cite>False</cite>.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.debug_log_format">
<tt class="descname">debug_log_format</tt><em class="property"> = '--------------------------------------------------------------------------------\n%(levelname)s in %(module)s [%(pathname)s:%(lineno)d]:\n%(message)s\n--------------------------------------------------------------------------------'</em><a class="headerlink" href="#flask.Flask.debug_log_format" title="Permalink to this definition">¶</a></dt>
<dd><p>The logging format used for the debug logger.  This is only used when
the application is in debug mode, otherwise the attached logging
handler does the formatting.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.3.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.default_config">
<tt class="descname">default_config</tt><em class="property"> = ImmutableDict({'USE_X_SENDFILE': False, 'SESSION_COOKIE_PATH': None, 'SESSION_COOKIE_DOMAIN': None, 'SESSION_COOKIE_NAME': 'session', 'LOGGER_NAME': None, 'DEBUG': False, 'SECRET_KEY': None, 'MAX_CONTENT_LENGTH': None, 'APPLICATION_ROOT': None, 'SERVER_NAME': None, 'TESTING': False, 'PERMANENT_SESSION_LIFETIME': datetime.timedelta(31), 'PROPAGATE_EXCEPTIONS': None, 'TRAP_BAD_REQUEST_ERRORS': False, 'TRAP_HTTP_EXCEPTIONS': False, 'PRESERVE_CONTEXT_ON_EXCEPTION': None, 'SESSION_COOKIE_SECURE': False, 'SESSION_COOKIE_HTTPONLY': True})</em><a class="headerlink" href="#flask.Flask.default_config" title="Permalink to this definition">¶</a></dt>
<dd><p>Default configuration parameters.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.dispatch_request">
<tt class="descname">dispatch_request</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.Flask.dispatch_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Does the request dispatching.  Matches the URL and returns the
return value of the view or error handler.  This does not have to
be a response object.  In order to convert the return value to a
proper response object, call <a class="reference internal" href="#flask.make_response" title="flask.make_response"><tt class="xref py py-func docutils literal"><span class="pre">make_response()</span></tt></a>.</p>
<p class="versionchanged">
<span class="versionmodified">Changed in version 0.7: </span>This no longer does the exception handling, this code was
moved to the new <a class="reference internal" href="#flask.Flask.full_dispatch_request" title="flask.Flask.full_dispatch_request"><tt class="xref py py-meth docutils literal"><span class="pre">full_dispatch_request()</span></tt></a>.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.do_teardown_request">
<tt class="descname">do_teardown_request</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.Flask.do_teardown_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Called after the actual request dispatching and will
call every as <a class="reference internal" href="#flask.Flask.teardown_request" title="flask.Flask.teardown_request"><tt class="xref py py-meth docutils literal"><span class="pre">teardown_request()</span></tt></a> decorated function.  This is
not actually called by the <a class="reference internal" href="#flask.Flask" title="flask.Flask"><tt class="xref py py-class docutils literal"><span class="pre">Flask</span></tt></a> object itself but is always
triggered when the request context is popped.  That way we have a
tighter control over certain resources under testing environments.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.enable_modules">
<tt class="descname">enable_modules</tt><em class="property"> = True</em><a class="headerlink" href="#flask.Flask.enable_modules" title="Permalink to this definition">¶</a></dt>
<dd><p>Enable the deprecated module support?  This is active by default
in 0.7 but will be changed to False in 0.8.  With Flask 1.0 modules
will be removed in favor of Blueprints</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.endpoint">
<tt class="descname">endpoint</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.Flask.endpoint" title="Permalink to this definition">¶</a></dt>
<dd><p>A decorator to register a function as an endpoint.
Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="nd">@app.endpoint</span><span class="p">(</span><span class="s">&#39;example.endpoint&#39;</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">example</span><span class="p">():</span>
    <span class="k">return</span> <span class="s">&quot;example&quot;</span>
</pre></div>
</div>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>endpoint</strong> &#8211; the name of the endpoint</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.error_handler_spec">
<tt class="descname">error_handler_spec</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.error_handler_spec" title="Permalink to this definition">¶</a></dt>
<dd><p>A dictionary of all registered error handlers.  The key is <cite>None</cite>
for error handlers active on the application, otherwise the key is
the name of the blueprint.  Each key points to another dictionary
where they key is the status code of the http exception.  The
special key <cite>None</cite> points to a list of tuples where the first item
is the class for the instance check and the second the error handler
function.</p>
<p>To register a error handler, use the <a class="reference internal" href="#flask.Flask.errorhandler" title="flask.Flask.errorhandler"><tt class="xref py py-meth docutils literal"><span class="pre">errorhandler()</span></tt></a>
decorator.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.errorhandler">
<tt class="descname">errorhandler</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.Flask.errorhandler" title="Permalink to this definition">¶</a></dt>
<dd><p>A decorator that is used to register a function give a given
error code.  Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="nd">@app.errorhandler</span><span class="p">(</span><span class="mi">404</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">page_not_found</span><span class="p">(</span><span class="n">error</span><span class="p">):</span>
    <span class="k">return</span> <span class="s">&#39;This page does not exist&#39;</span><span class="p">,</span> <span class="mi">404</span>
</pre></div>
</div>
<p>You can also register handlers for arbitrary exceptions:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="nd">@app.errorhandler</span><span class="p">(</span><span class="n">DatabaseError</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">special_exception_handler</span><span class="p">(</span><span class="n">error</span><span class="p">):</span>
    <span class="k">return</span> <span class="s">&#39;Database connection failed&#39;</span><span class="p">,</span> <span class="mi">500</span>
</pre></div>
</div>
<p>You can also register a function as error handler without using
the <a class="reference internal" href="#flask.Flask.errorhandler" title="flask.Flask.errorhandler"><tt class="xref py py-meth docutils literal"><span class="pre">errorhandler()</span></tt></a> decorator.  The following example is
equivalent to the one above:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">def</span> <span class="nf">page_not_found</span><span class="p">(</span><span class="n">error</span><span class="p">):</span>
    <span class="k">return</span> <span class="s">&#39;This page does not exist&#39;</span><span class="p">,</span> <span class="mi">404</span>
<span class="n">app</span><span class="o">.</span><span class="n">error_handler_spec</span><span class="p">[</span><span class="bp">None</span><span class="p">][</span><span class="mi">404</span><span class="p">]</span> <span class="o">=</span> <span class="n">page_not_found</span>
</pre></div>
</div>
<p>Setting error handlers via assignments to <a class="reference internal" href="#flask.Flask.error_handler_spec" title="flask.Flask.error_handler_spec"><tt class="xref py py-attr docutils literal"><span class="pre">error_handler_spec</span></tt></a>
however is discouraged as it requires fidling with nested dictionaries
and the special case for arbitrary exception types.</p>
<p>The first <cite>None</cite> refers to the active blueprint.  If the error
handler should be application wide <cite>None</cite> shall be used.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7: </span>One can now additionally also register custom exception types
that do not necessarily have to be a subclass of the
<tt class="xref py py-class docutils literal"><span class="pre">HTTPException</span></tt> class.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>code</strong> &#8211; the code as integer for the handler</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.extensions">
<tt class="descname">extensions</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.extensions" title="Permalink to this definition">¶</a></dt>
<dd><p>a place where extensions can store application specific state.  For
example this is where an extension could store database engines and
similar things.  For backwards compatibility extensions should register
themselves like this:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">if</span> <span class="ow">not</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">app</span><span class="p">,</span> <span class="s">&#39;extensions&#39;</span><span class="p">):</span>
    <span class="n">app</span><span class="o">.</span><span class="n">extensions</span> <span class="o">=</span> <span class="p">{}</span>
<span class="n">app</span><span class="o">.</span><span class="n">extensions</span><span class="p">[</span><span class="s">&#39;extensionname&#39;</span><span class="p">]</span> <span class="o">=</span> <span class="n">SomeObject</span><span class="p">()</span>
</pre></div>
</div>
<p>The key must match the name of the <cite>flaskext</cite> module.  For example in
case of a &#8220;Flask-Foo&#8221; extension in <cite>flaskext.foo</cite>, the key would be
<tt class="docutils literal"><span class="pre">'foo'</span></tt>.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.full_dispatch_request">
<tt class="descname">full_dispatch_request</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.Flask.full_dispatch_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Dispatches the request and on top of that performs request
pre and postprocessing as well as HTTP exception catching and
error handling.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.got_first_request">
<tt class="descname">got_first_request</tt><a class="headerlink" href="#flask.Flask.got_first_request" title="Permalink to this definition">¶</a></dt>
<dd><p>This attribute is set to <cite>True</cite> if the application started
handling the first request.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.handle_exception">
<tt class="descname">handle_exception</tt><big>(</big><em>e</em><big>)</big><a class="headerlink" href="#flask.Flask.handle_exception" title="Permalink to this definition">¶</a></dt>
<dd><p>Default exception handling that kicks in when an exception
occours that is not caught.  In debug mode the exception will
be re-raised immediately, otherwise it is logged and the handler
for a 500 internal server error is used.  If no such handler
exists, a default 500 internal server error message is displayed.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.handle_http_exception">
<tt class="descname">handle_http_exception</tt><big>(</big><em>e</em><big>)</big><a class="headerlink" href="#flask.Flask.handle_http_exception" title="Permalink to this definition">¶</a></dt>
<dd><p>Handles an HTTP exception.  By default this will invoke the
registered error handlers and fall back to returning the
exception as response.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.handle_user_exception">
<tt class="descname">handle_user_exception</tt><big>(</big><em>e</em><big>)</big><a class="headerlink" href="#flask.Flask.handle_user_exception" title="Permalink to this definition">¶</a></dt>
<dd><p>This method is called whenever an exception occurs that should be
handled.  A special case are
<tt class="xref py py-class docutils literal"><span class="pre">HTTPException</span></tt>s which are forwarded by
this function to the <a class="reference internal" href="#flask.Flask.handle_http_exception" title="flask.Flask.handle_http_exception"><tt class="xref py py-meth docutils literal"><span class="pre">handle_http_exception()</span></tt></a> method.  This
function will either return a response value or reraise the
exception with the same traceback.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.has_static_folder">
<tt class="descname">has_static_folder</tt><a class="headerlink" href="#flask.Flask.has_static_folder" title="Permalink to this definition">¶</a></dt>
<dd><p>This is <cite>True</cite> if the package bound object&#8217;s container has a
folder named <tt class="docutils literal"><span class="pre">'static'</span></tt>.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.5.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.init_jinja_globals">
<tt class="descname">init_jinja_globals</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.Flask.init_jinja_globals" title="Permalink to this definition">¶</a></dt>
<dd><p>Deprecated.  Used to initialize the Jinja2 globals.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.5.</span></p>
<p class="versionchanged">
<span class="versionmodified">Changed in version 0.7: </span>This method is deprecated with 0.7.  Override
<a class="reference internal" href="#flask.Flask.create_jinja_environment" title="flask.Flask.create_jinja_environment"><tt class="xref py py-meth docutils literal"><span class="pre">create_jinja_environment()</span></tt></a> instead.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.inject_url_defaults">
<tt class="descname">inject_url_defaults</tt><big>(</big><em>endpoint</em>, <em>values</em><big>)</big><a class="headerlink" href="#flask.Flask.inject_url_defaults" title="Permalink to this definition">¶</a></dt>
<dd><p>Injects the URL defaults for the given endpoint directly into
the values dictionary passed.  This is used internally and
automatically called on URL building.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.instance_path">
<tt class="descname">instance_path</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.instance_path" title="Permalink to this definition">¶</a></dt>
<dd><p>Holds the path to the instance folder.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.jinja_env">
<tt class="descname">jinja_env</tt><a class="headerlink" href="#flask.Flask.jinja_env" title="Permalink to this definition">¶</a></dt>
<dd><p>The Jinja2 environment used to load templates.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.jinja_loader">
<tt class="descname">jinja_loader</tt><a class="headerlink" href="#flask.Flask.jinja_loader" title="Permalink to this definition">¶</a></dt>
<dd><p>The Jinja loader for this package bound object.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.5.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.jinja_options">
<tt class="descname">jinja_options</tt><em class="property"> = ImmutableDict({'extensions': ['jinja2.ext.autoescape', 'jinja2.ext.with_']})</em><a class="headerlink" href="#flask.Flask.jinja_options" title="Permalink to this definition">¶</a></dt>
<dd><p>Options that are passed directly to the Jinja2 environment.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.log_exception">
<tt class="descname">log_exception</tt><big>(</big><em>exc_info</em><big>)</big><a class="headerlink" href="#flask.Flask.log_exception" title="Permalink to this definition">¶</a></dt>
<dd><p>Logs an exception.  This is called by <a class="reference internal" href="#flask.Flask.handle_exception" title="flask.Flask.handle_exception"><tt class="xref py py-meth docutils literal"><span class="pre">handle_exception()</span></tt></a>
if debugging is disabled and right before the handler is called.
The default implementation logs the exception as error on the
<a class="reference internal" href="#flask.Flask.logger" title="flask.Flask.logger"><tt class="xref py py-attr docutils literal"><span class="pre">logger</span></tt></a>.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.logger">
<tt class="descname">logger</tt><a class="headerlink" href="#flask.Flask.logger" title="Permalink to this definition">¶</a></dt>
<dd><p>A <a class="reference external" href="http://docs.python.org/dev/library/logging.html#logging.Logger" title="(in Python v3.3)"><tt class="xref py py-class docutils literal"><span class="pre">logging.Logger</span></tt></a> object for this application.  The
default configuration is to log to stderr if the application is
in debug mode.  This logger can be used to (surprise) log messages.
Here some examples:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">app</span><span class="o">.</span><span class="n">logger</span><span class="o">.</span><span class="n">debug</span><span class="p">(</span><span class="s">&#39;A value for debugging&#39;</span><span class="p">)</span>
<span class="n">app</span><span class="o">.</span><span class="n">logger</span><span class="o">.</span><span class="n">warning</span><span class="p">(</span><span class="s">&#39;A warning ocurred (</span><span class="si">%d</span><span class="s"> apples)&#39;</span><span class="p">,</span> <span class="mi">42</span><span class="p">)</span>
<span class="n">app</span><span class="o">.</span><span class="n">logger</span><span class="o">.</span><span class="n">error</span><span class="p">(</span><span class="s">&#39;An error occoured&#39;</span><span class="p">)</span>
</pre></div>
</div>
<p class="versionadded">
<span class="versionmodified">New in version 0.3.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.logger_name">
<tt class="descname">logger_name</tt><a class="headerlink" href="#flask.Flask.logger_name" title="Permalink to this definition">¶</a></dt>
<dd><p>The name of the logger to use.  By default the logger name is the
package name passed to the constructor.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.4.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.make_config">
<tt class="descname">make_config</tt><big>(</big><em>instance_relative=False</em><big>)</big><a class="headerlink" href="#flask.Flask.make_config" title="Permalink to this definition">¶</a></dt>
<dd><p>Used to create the config attribute by the Flask constructor.
The <cite>instance_relative</cite> parameter is passed in from the constructor
of Flask (there named <cite>instance_relative_config</cite>) and indicates if
the config should be relative to the instance path or the root path
of the application.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.make_default_options_response">
<tt class="descname">make_default_options_response</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.Flask.make_default_options_response" title="Permalink to this definition">¶</a></dt>
<dd><p>This method is called to create the default <cite>OPTIONS</cite> response.
This can be changed through subclassing to change the default
behaviour of <cite>OPTIONS</cite> responses.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.make_null_session">
<tt class="descname">make_null_session</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.Flask.make_null_session" title="Permalink to this definition">¶</a></dt>
<dd><p>Creates a new instance of a missing session.  Instead of overriding
this method we recommend replacing the <a class="reference internal" href="#flask.Flask.session_interface" title="flask.Flask.session_interface"><tt class="xref py py-class docutils literal"><span class="pre">session_interface</span></tt></a>.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.make_response">
<tt class="descname">make_response</tt><big>(</big><em>rv</em><big>)</big><a class="headerlink" href="#flask.Flask.make_response" title="Permalink to this definition">¶</a></dt>
<dd><p>Converts the return value from a view function to a real
response object that is an instance of <a class="reference internal" href="#flask.Flask.response_class" title="flask.Flask.response_class"><tt class="xref py py-attr docutils literal"><span class="pre">response_class</span></tt></a>.</p>
<p>The following types are allowed for <cite>rv</cite>:</p>
<table border="1" class="docutils">
<colgroup>
<col width="35%" />
<col width="65%" />
</colgroup>
<tbody valign="top">
<tr class="row-odd"><td><a class="reference internal" href="#flask.Flask.response_class" title="flask.Flask.response_class"><tt class="xref py py-attr docutils literal"><span class="pre">response_class</span></tt></a></td>
<td>the object is returned unchanged</td>
</tr>
<tr class="row-even"><td><tt class="xref py py-class docutils literal"><span class="pre">str</span></tt></td>
<td>a response object is created with the
string as body</td>
</tr>
<tr class="row-odd"><td><tt class="xref py py-class docutils literal"><span class="pre">unicode</span></tt></td>
<td>a response object is created with the
string encoded to utf-8 as body</td>
</tr>
<tr class="row-even"><td><tt class="xref py py-class docutils literal"><span class="pre">tuple</span></tt></td>
<td>the response object is created with the
contents of the tuple as arguments</td>
</tr>
<tr class="row-odd"><td>a WSGI function</td>
<td>the function is called as WSGI application
and buffered as response object</td>
</tr>
</tbody>
</table>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>rv</strong> &#8211; the return value from the view function</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.name">
<tt class="descname">name</tt><a class="headerlink" href="#flask.Flask.name" title="Permalink to this definition">¶</a></dt>
<dd><p>The name of the application.  This is usually the import name
with the difference that it&#8217;s guessed from the run file if the
import name is main.  This name is used as a display name when
Flask needs the name of the application.  It can be set and overriden
to change the value.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.open_instance_resource">
<tt class="descname">open_instance_resource</tt><big>(</big><em>resource</em>, <em>mode='rb'</em><big>)</big><a class="headerlink" href="#flask.Flask.open_instance_resource" title="Permalink to this definition">¶</a></dt>
<dd><p>Opens a resource from the application&#8217;s instance folder
(<a class="reference internal" href="#flask.Flask.instance_path" title="flask.Flask.instance_path"><tt class="xref py py-attr docutils literal"><span class="pre">instance_path</span></tt></a>).  Otherwise works like
<a class="reference internal" href="#flask.Flask.open_resource" title="flask.Flask.open_resource"><tt class="xref py py-meth docutils literal"><span class="pre">open_resource()</span></tt></a>.  Instance resources can also be opened for
writing.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>resource</strong> &#8211; the name of the resource.  To access resources within
subfolders use forward slashes as separator.</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.open_resource">
<tt class="descname">open_resource</tt><big>(</big><em>resource</em>, <em>mode='rb'</em><big>)</big><a class="headerlink" href="#flask.Flask.open_resource" title="Permalink to this definition">¶</a></dt>
<dd><p>Opens a resource from the application&#8217;s resource folder.  To see
how this works, consider the following folder structure:</p>
<div class="highlight-python"><pre>/myapplication.py
/schema.sql
/static
    /style.css
/templates
    /layout.html
    /index.html</pre>
</div>
<p>If you want to open the <cite>schema.sql</cite> file you would do the
following:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">with</span> <span class="n">app</span><span class="o">.</span><span class="n">open_resource</span><span class="p">(</span><span class="s">&#39;schema.sql&#39;</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span>
    <span class="n">contents</span> <span class="o">=</span> <span class="n">f</span><span class="o">.</span><span class="n">read</span><span class="p">()</span>
    <span class="n">do_something_with</span><span class="p">(</span><span class="n">contents</span><span class="p">)</span>
</pre></div>
</div>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>resource</strong> &#8211; the name of the resource.  To access resources within
subfolders use forward slashes as separator.</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.open_session">
<tt class="descname">open_session</tt><big>(</big><em>request</em><big>)</big><a class="headerlink" href="#flask.Flask.open_session" title="Permalink to this definition">¶</a></dt>
<dd><p>Creates or opens a new session.  Default implementation stores all
session data in a signed cookie.  This requires that the
<a class="reference internal" href="#flask.Flask.secret_key" title="flask.Flask.secret_key"><tt class="xref py py-attr docutils literal"><span class="pre">secret_key</span></tt></a> is set.  Instead of overriding this method
we recommend replacing the <a class="reference internal" href="#flask.Flask.session_interface" title="flask.Flask.session_interface"><tt class="xref py py-class docutils literal"><span class="pre">session_interface</span></tt></a>.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>request</strong> &#8211; an instance of <a class="reference internal" href="#flask.Flask.request_class" title="flask.Flask.request_class"><tt class="xref py py-attr docutils literal"><span class="pre">request_class</span></tt></a>.</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.permanent_session_lifetime">
<tt class="descname">permanent_session_lifetime</tt><a class="headerlink" href="#flask.Flask.permanent_session_lifetime" title="Permalink to this definition">¶</a></dt>
<dd><p>A <a class="reference external" href="http://docs.python.org/dev/library/datetime.html#datetime.timedelta" title="(in Python v3.3)"><tt class="xref py py-class docutils literal"><span class="pre">timedelta</span></tt></a> which is used to set the expiration
date of a permanent session.  The default is 31 days which makes a
permanent session survive for roughly one month.</p>
<p>This attribute can also be configured from the config with the
<cite>PERMANENT_SESSION_LIFETIME</cite> configuration key.  Defaults to
<tt class="docutils literal"><span class="pre">timedelta(days=31)</span></tt></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.preprocess_request">
<tt class="descname">preprocess_request</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.Flask.preprocess_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Called before the actual request dispatching and will
call every as <a class="reference internal" href="#flask.Flask.before_request" title="flask.Flask.before_request"><tt class="xref py py-meth docutils literal"><span class="pre">before_request()</span></tt></a> decorated function.
If any of these function returns a value it&#8217;s handled as
if it was the return value from the view and further
request handling is stopped.</p>
<p>This also triggers the <tt class="xref py py-meth docutils literal"><span class="pre">url_value_processor()</span></tt> functions before
the actualy <a class="reference internal" href="#flask.Flask.before_request" title="flask.Flask.before_request"><tt class="xref py py-meth docutils literal"><span class="pre">before_request()</span></tt></a> functions are called.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.preserve_context_on_exception">
<tt class="descname">preserve_context_on_exception</tt><a class="headerlink" href="#flask.Flask.preserve_context_on_exception" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns the value of the <cite>PRESERVE_CONTEXT_ON_EXCEPTION</cite>
configuration value in case it&#8217;s set, otherwise a sensible default
is returned.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.process_response">
<tt class="descname">process_response</tt><big>(</big><em>response</em><big>)</big><a class="headerlink" href="#flask.Flask.process_response" title="Permalink to this definition">¶</a></dt>
<dd><p>Can be overridden in order to modify the response object
before it&#8217;s sent to the WSGI server.  By default this will
call all the <a class="reference internal" href="#flask.Flask.after_request" title="flask.Flask.after_request"><tt class="xref py py-meth docutils literal"><span class="pre">after_request()</span></tt></a> decorated functions.</p>
<p class="versionchanged">
<span class="versionmodified">Changed in version 0.5: </span>As of Flask 0.5 the functions registered for after request
execution are called in reverse order of registration.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>response</strong> &#8211; a <a class="reference internal" href="#flask.Flask.response_class" title="flask.Flask.response_class"><tt class="xref py py-attr docutils literal"><span class="pre">response_class</span></tt></a> object.</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body">a new response object or the same, has to be an
instance of <a class="reference internal" href="#flask.Flask.response_class" title="flask.Flask.response_class"><tt class="xref py py-attr docutils literal"><span class="pre">response_class</span></tt></a>.</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.propagate_exceptions">
<tt class="descname">propagate_exceptions</tt><a class="headerlink" href="#flask.Flask.propagate_exceptions" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns the value of the <cite>PROPAGATE_EXCEPTIONS</cite> configuration
value in case it&#8217;s set, otherwise a sensible default is returned.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.register_blueprint">
<tt class="descname">register_blueprint</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.Flask.register_blueprint" title="Permalink to this definition">¶</a></dt>
<dd><p>Registers a blueprint on the application.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.register_error_handler">
<tt class="descname">register_error_handler</tt><big>(</big><em>code_or_exception</em>, <em>f</em><big>)</big><a class="headerlink" href="#flask.Flask.register_error_handler" title="Permalink to this definition">¶</a></dt>
<dd><p>Alternative error attach function to the <a class="reference internal" href="#flask.Flask.errorhandler" title="flask.Flask.errorhandler"><tt class="xref py py-meth docutils literal"><span class="pre">errorhandler()</span></tt></a>
decorator that is more straightforward to use for non decorator
usage.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.register_module">
<tt class="descname">register_module</tt><big>(</big><em>module</em>, <em>**options</em><big>)</big><a class="headerlink" href="#flask.Flask.register_module" title="Permalink to this definition">¶</a></dt>
<dd><p>Registers a module with this application.  The keyword argument
of this function are the same as the ones for the constructor of the
<tt class="xref py py-class docutils literal"><span class="pre">Module</span></tt> class and will override the values of the module if
provided.</p>
<p class="versionchanged">
<span class="versionmodified">Changed in version 0.7: </span>The module system was deprecated in favor for the blueprint
system.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.request_class">
<tt class="descname">request_class</tt><a class="headerlink" href="#flask.Flask.request_class" title="Permalink to this definition">¶</a></dt>
<dd><p>The class that is used for request objects.  See <a class="reference internal" href="#flask.Request" title="flask.Request"><tt class="xref py py-class docutils literal"><span class="pre">Request</span></tt></a>
for more information.</p>
<p>alias of <a class="reference internal" href="#flask.Request" title="flask.Request"><tt class="xref py py-class docutils literal"><span class="pre">Request</span></tt></a></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.request_context">
<tt class="descname">request_context</tt><big>(</big><em>environ</em><big>)</big><a class="headerlink" href="#flask.Flask.request_context" title="Permalink to this definition">¶</a></dt>
<dd><p>Creates a <a class="reference internal" href="#flask.ctx.RequestContext" title="flask.ctx.RequestContext"><tt class="xref py py-class docutils literal"><span class="pre">RequestContext</span></tt></a> from the given
environment and binds it to the current context.  This must be used in
combination with the <cite>with</cite> statement because the request is only bound
to the current context for the duration of the <cite>with</cite> block.</p>
<p>Example usage:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">with</span> <span class="n">app</span><span class="o">.</span><span class="n">request_context</span><span class="p">(</span><span class="n">environ</span><span class="p">):</span>
    <span class="n">do_something_with</span><span class="p">(</span><span class="n">request</span><span class="p">)</span>
</pre></div>
</div>
<p>The object returned can also be used without the <cite>with</cite> statement
which is useful for working in the shell.  The example above is
doing exactly the same as this code:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">ctx</span> <span class="o">=</span> <span class="n">app</span><span class="o">.</span><span class="n">request_context</span><span class="p">(</span><span class="n">environ</span><span class="p">)</span>
<span class="n">ctx</span><span class="o">.</span><span class="n">push</span><span class="p">()</span>
<span class="k">try</span><span class="p">:</span>
    <span class="n">do_something_with</span><span class="p">(</span><span class="n">request</span><span class="p">)</span>
<span class="k">finally</span><span class="p">:</span>
    <span class="n">ctx</span><span class="o">.</span><span class="n">pop</span><span class="p">()</span>
</pre></div>
</div>
<p class="versionchanged">
<span class="versionmodified">Changed in version 0.3: </span>Added support for non-with statement usage and <cite>with</cite> statement
is now passed the ctx object.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>environ</strong> &#8211; a WSGI environment</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.response_class">
<tt class="descname">response_class</tt><a class="headerlink" href="#flask.Flask.response_class" title="Permalink to this definition">¶</a></dt>
<dd><p>The class that is used for response objects.  See
<a class="reference internal" href="#flask.Response" title="flask.Response"><tt class="xref py py-class docutils literal"><span class="pre">Response</span></tt></a> for more information.</p>
<p>alias of <a class="reference internal" href="#flask.Response" title="flask.Response"><tt class="xref py py-class docutils literal"><span class="pre">Response</span></tt></a></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.route">
<tt class="descname">route</tt><big>(</big><em>rule</em>, <em>**options</em><big>)</big><a class="headerlink" href="#flask.Flask.route" title="Permalink to this definition">¶</a></dt>
<dd><p>A decorator that is used to register a view function for a
given URL rule.  This does the same thing as <a class="reference internal" href="#flask.Flask.add_url_rule" title="flask.Flask.add_url_rule"><tt class="xref py py-meth docutils literal"><span class="pre">add_url_rule()</span></tt></a>
but is intended for decorator usage:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="nd">@app.route</span><span class="p">(</span><span class="s">&#39;/&#39;</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">index</span><span class="p">():</span>
    <span class="k">return</span> <span class="s">&#39;Hello World&#39;</span>
</pre></div>
</div>
<p>For more information refer to <a class="reference internal" href="#url-route-registrations"><em>URL Route Registrations</em></a>.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>rule</strong> &#8211; the URL rule as string</li>
<li><strong>endpoint</strong> &#8211; the endpoint for the registered URL rule.  Flask
itself assumes the name of the view function as
endpoint</li>
<li><strong>view_func</strong> &#8211; the function to call when serving a request to the
provided endpoint</li>
<li><strong>options</strong> &#8211; the options to be forwarded to the underlying
<a class="reference external" href="http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Rule" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">Rule</span></tt></a> object.  A change
to Werkzeug is handling of method options.  methods
is a list of methods this rule should be limited
to (<cite>GET</cite>, <cite>POST</cite> etc.).  By default a rule
just listens for <cite>GET</cite> (and implicitly <cite>HEAD</cite>).
Starting with Flask 0.6, <cite>OPTIONS</cite> is implicitly
added and handled by the standard request handling.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.run">
<tt class="descname">run</tt><big>(</big><em>host='127.0.0.1'</em>, <em>port=5000</em>, <em>debug=None</em>, <em>**options</em><big>)</big><a class="headerlink" href="#flask.Flask.run" title="Permalink to this definition">¶</a></dt>
<dd><p>Runs the application on a local development server.  If the
<a class="reference internal" href="#flask.Flask.debug" title="flask.Flask.debug"><tt class="xref py py-attr docutils literal"><span class="pre">debug</span></tt></a> flag is set the server will automatically reload
for code changes and show a debugger in case an exception happened.</p>
<p>If you want to run the application in debug mode, but disable the
code execution on the interactive debugger, you can pass
<tt class="docutils literal"><span class="pre">use_evalex=False</span></tt> as parameter.  This will keep the debugger&#8217;s
traceback screen active, but disable code execution.</p>
<div class="admonition-keep-in-mind admonition ">
<p class="first admonition-title">Keep in Mind</p>
<p class="last">Flask will suppress any server error with a generic error page
unless it is in debug mode.  As such to enable just the
interactive debugger without the code reloading, you have to
invoke <a class="reference internal" href="#flask.Flask.run" title="flask.Flask.run"><tt class="xref py py-meth docutils literal"><span class="pre">run()</span></tt></a> with <tt class="docutils literal"><span class="pre">debug=True</span></tt> and <tt class="docutils literal"><span class="pre">use_reloader=False</span></tt>.
Setting <tt class="docutils literal"><span class="pre">use_debugger</span></tt> to <cite>True</cite> without being in debug mode
won&#8217;t catch any exceptions because there won&#8217;t be any to
catch.</p>
</div>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>host</strong> &#8211; the hostname to listen on.  set this to <tt class="docutils literal"><span class="pre">'0.0.0.0'</span></tt>
to have the server available externally as well.</li>
<li><strong>port</strong> &#8211; the port of the webserver</li>
<li><strong>debug</strong> &#8211; if given, enable or disable debug mode.
See <a class="reference internal" href="#flask.Flask.debug" title="flask.Flask.debug"><tt class="xref py py-attr docutils literal"><span class="pre">debug</span></tt></a>.</li>
<li><strong>options</strong> &#8211; the options to be forwarded to the underlying
Werkzeug server.  See
<a class="reference external" href="http://werkzeug.pocoo.org/docs/serving/#werkzeug.serving.run_simple" title="(in Werkzeug v0.7)"><tt class="xref py py-func docutils literal"><span class="pre">werkzeug.serving.run_simple()</span></tt></a> for more
information.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.save_session">
<tt class="descname">save_session</tt><big>(</big><em>session</em>, <em>response</em><big>)</big><a class="headerlink" href="#flask.Flask.save_session" title="Permalink to this definition">¶</a></dt>
<dd><p>Saves the session if it needs updates.  For the default
implementation, check <a class="reference internal" href="#flask.Flask.open_session" title="flask.Flask.open_session"><tt class="xref py py-meth docutils literal"><span class="pre">open_session()</span></tt></a>.  Instead of overriding this
method we recommend replacing the <a class="reference internal" href="#flask.Flask.session_interface" title="flask.Flask.session_interface"><tt class="xref py py-class docutils literal"><span class="pre">session_interface</span></tt></a>.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>session</strong> &#8211; the session to be saved (a
<a class="reference external" href="http://werkzeug.pocoo.org/docs/contrib/securecookie/#werkzeug.contrib.securecookie.SecureCookie" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">SecureCookie</span></tt></a>
object)</li>
<li><strong>response</strong> &#8211; an instance of <a class="reference internal" href="#flask.Flask.response_class" title="flask.Flask.response_class"><tt class="xref py py-attr docutils literal"><span class="pre">response_class</span></tt></a></li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.secret_key">
<tt class="descname">secret_key</tt><a class="headerlink" href="#flask.Flask.secret_key" title="Permalink to this definition">¶</a></dt>
<dd><p>If a secret key is set, cryptographic components can use this to
sign cookies and other things.  Set this to a complex random value
when you want to use the secure cookie for instance.</p>
<p>This attribute can also be configured from the config with the
<cite>SECRET_KEY</cite> configuration key.  Defaults to <cite>None</cite>.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.select_jinja_autoescape">
<tt class="descname">select_jinja_autoescape</tt><big>(</big><em>filename</em><big>)</big><a class="headerlink" href="#flask.Flask.select_jinja_autoescape" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns <cite>True</cite> if autoescaping should be active for the given
template name.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.5.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.send_static_file">
<tt class="descname">send_static_file</tt><big>(</big><em>filename</em><big>)</big><a class="headerlink" href="#flask.Flask.send_static_file" title="Permalink to this definition">¶</a></dt>
<dd><p>Function used internally to send static files from the static
folder to the browser.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.5.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.session_cookie_name">
<tt class="descname">session_cookie_name</tt><a class="headerlink" href="#flask.Flask.session_cookie_name" title="Permalink to this definition">¶</a></dt>
<dd><p>The secure cookie uses this for the name of the session cookie.</p>
<p>This attribute can also be configured from the config with the
<cite>SESSION_COOKIE_NAME</cite> configuration key.  Defaults to <tt class="docutils literal"><span class="pre">'session'</span></tt></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.session_interface">
<tt class="descname">session_interface</tt><em class="property"> = &lt;flask.sessions.SecureCookieSessionInterface object at 0x103dc8090&gt;</em><a class="headerlink" href="#flask.Flask.session_interface" title="Permalink to this definition">¶</a></dt>
<dd><p>the session interface to use.  By default an instance of
<a class="reference internal" href="#flask.sessions.SecureCookieSessionInterface" title="flask.sessions.SecureCookieSessionInterface"><tt class="xref py py-class docutils literal"><span class="pre">SecureCookieSessionInterface</span></tt></a> is used here.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.teardown_request">
<tt class="descname">teardown_request</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.Flask.teardown_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Register a function to be run at the end of each request,
regardless of whether there was an exception or not.  These functions
are executed when the request context is popped, even if not an
actual request was performed.</p>
<p>Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">ctx</span> <span class="o">=</span> <span class="n">app</span><span class="o">.</span><span class="n">test_request_context</span><span class="p">()</span>
<span class="n">ctx</span><span class="o">.</span><span class="n">push</span><span class="p">()</span>
<span class="o">...</span>
<span class="n">ctx</span><span class="o">.</span><span class="n">pop</span><span class="p">()</span>
</pre></div>
</div>
<p>When <tt class="docutils literal"><span class="pre">ctx.pop()</span></tt> is executed in the above example, the teardown
functions are called just before the request context moves from the
stack of active contexts.  This becomes relevant if you are using
such constructs in tests.</p>
<p>Generally teardown functions must take every necesary step to avoid
that they will fail.  If they do execute code that might fail they
will have to surround the execution of these code by try/except
statements and log ocurring errors.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.teardown_request_funcs">
<tt class="descname">teardown_request_funcs</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.teardown_request_funcs" title="Permalink to this definition">¶</a></dt>
<dd><p>A dictionary with lists of functions that are called after
each request, even if an exception has occurred. The key of the
dictionary is the name of the blueprint this function is active for,
<cite>None</cite> for all requests. These functions are not allowed to modify
the request, and their return values are ignored. If an exception
occurred while processing the request, it gets passed to each
teardown_request function. To register a function here, use the
<a class="reference internal" href="#flask.Flask.teardown_request" title="flask.Flask.teardown_request"><tt class="xref py py-meth docutils literal"><span class="pre">teardown_request()</span></tt></a> decorator.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.template_context_processors">
<tt class="descname">template_context_processors</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.template_context_processors" title="Permalink to this definition">¶</a></dt>
<dd><p>A dictionary with list of functions that are called without argument
to populate the template context.  The key of the dictionary is the
name of the blueprint this function is active for, <cite>None</cite> for all
requests.  Each returns a dictionary that the template context is
updated with.  To register a function here, use the
<a class="reference internal" href="#flask.Flask.context_processor" title="flask.Flask.context_processor"><tt class="xref py py-meth docutils literal"><span class="pre">context_processor()</span></tt></a> decorator.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.template_filter">
<tt class="descname">template_filter</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.Flask.template_filter" title="Permalink to this definition">¶</a></dt>
<dd><p>A decorator that is used to register custom template filter.
You can specify a name for the filter, otherwise the function
name will be used. Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="nd">@app.template_filter</span><span class="p">()</span>
<span class="k">def</span> <span class="nf">reverse</span><span class="p">(</span><span class="n">s</span><span class="p">):</span>
    <span class="k">return</span> <span class="n">s</span><span class="p">[::</span><span class="o">-</span><span class="mi">1</span><span class="p">]</span>
</pre></div>
</div>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>name</strong> &#8211; the optional name of the filter, otherwise the
function name will be used.</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.test_client">
<tt class="descname">test_client</tt><big>(</big><em>use_cookies=True</em><big>)</big><a class="headerlink" href="#flask.Flask.test_client" title="Permalink to this definition">¶</a></dt>
<dd><p>Creates a test client for this application.  For information
about unit testing head over to <a class="reference internal" href="testing.html#testing"><em>Testing Flask Applications</em></a>.</p>
<p>The test client can be used in a <cite>with</cite> block to defer the closing down
of the context until the end of the <cite>with</cite> block.  This is useful if
you want to access the context locals for testing:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">with</span> <span class="n">app</span><span class="o">.</span><span class="n">test_client</span><span class="p">()</span> <span class="k">as</span> <span class="n">c</span><span class="p">:</span>
    <span class="n">rv</span> <span class="o">=</span> <span class="n">c</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="s">&#39;/?vodka=42&#39;</span><span class="p">)</span>
    <span class="k">assert</span> <span class="n">request</span><span class="o">.</span><span class="n">args</span><span class="p">[</span><span class="s">&#39;vodka&#39;</span><span class="p">]</span> <span class="o">==</span> <span class="s">&#39;42&#39;</span>
</pre></div>
</div>
<p>See <a class="reference internal" href="#flask.testing.FlaskClient" title="flask.testing.FlaskClient"><tt class="xref py py-class docutils literal"><span class="pre">FlaskClient</span></tt></a> for more information.</p>
<p class="versionchanged">
<span class="versionmodified">Changed in version 0.4: </span>added support for <cite>with</cite> block usage for the client.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7: </span>The <cite>use_cookies</cite> parameter was added as well as the ability
to override the client to be used by setting the
<a class="reference internal" href="#flask.Flask.test_client_class" title="flask.Flask.test_client_class"><tt class="xref py py-attr docutils literal"><span class="pre">test_client_class</span></tt></a> attribute.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.test_client_class">
<tt class="descname">test_client_class</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.test_client_class" title="Permalink to this definition">¶</a></dt>
<dd><p>the test client that is used with when <cite>test_client</cite> is used.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.test_request_context">
<tt class="descname">test_request_context</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.Flask.test_request_context" title="Permalink to this definition">¶</a></dt>
<dd><p>Creates a WSGI environment from the given values (see
<tt class="xref py py-func docutils literal"><span class="pre">werkzeug.test.EnvironBuilder()</span></tt> for more information, this
function accepts the same arguments).</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.testing">
<tt class="descname">testing</tt><a class="headerlink" href="#flask.Flask.testing" title="Permalink to this definition">¶</a></dt>
<dd><p>The testing flag.  Set this to <cite>True</cite> to enable the test mode of
Flask extensions (and in the future probably also Flask itself).
For example this might activate unittest helpers that have an
additional runtime cost which should not be enabled by default.</p>
<p>If this is enabled and PROPAGATE_EXCEPTIONS is not changed from the
default it&#8217;s implicitly enabled.</p>
<p>This attribute can also be configured from the config with the
<cite>TESTING</cite> configuration key.  Defaults to <cite>False</cite>.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.trap_http_exception">
<tt class="descname">trap_http_exception</tt><big>(</big><em>e</em><big>)</big><a class="headerlink" href="#flask.Flask.trap_http_exception" title="Permalink to this definition">¶</a></dt>
<dd><p>Checks if an HTTP exception should be trapped or not.  By default
this will return <cite>False</cite> for all exceptions except for a bad request
key error if <tt class="docutils literal"><span class="pre">TRAP_BAD_REQUEST_ERRORS</span></tt> is set to <cite>True</cite>.  It
also returns <cite>True</cite> if <tt class="docutils literal"><span class="pre">TRAP_HTTP_EXCEPTIONS</span></tt> is set to <cite>True</cite>.</p>
<p>This is called for all HTTP exceptions raised by a view function.
If it returns <cite>True</cite> for any exception the error handler for this
exception is not called and it shows up as regular exception in the
traceback.  This is helpful for debugging implicitly raised HTTP
exceptions.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.update_template_context">
<tt class="descname">update_template_context</tt><big>(</big><em>context</em><big>)</big><a class="headerlink" href="#flask.Flask.update_template_context" title="Permalink to this definition">¶</a></dt>
<dd><p>Update the template context with some commonly used variables.
This injects request, session, config and g into the template
context as well as everything template context processors want
to inject.  Note that the as of Flask 0.6, the original values
in the context will not be overriden if a context processor
decides to return a value with the same key.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>context</strong> &#8211; the context as a dictionary that is updated in place
to add extra variables.</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.url_default_functions">
<tt class="descname">url_default_functions</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.url_default_functions" title="Permalink to this definition">¶</a></dt>
<dd><p>A dictionary with lists of functions that can be used as URL value
preprocessors.  The key <cite>None</cite> here is used for application wide
callbacks, otherwise the key is the name of the blueprint.
Each of these functions has the chance to modify the dictionary
of URL values before they are used as the keyword arguments of the
view function.  For each function registered this one should also
provide a <a class="reference internal" href="#flask.Flask.url_defaults" title="flask.Flask.url_defaults"><tt class="xref py py-meth docutils literal"><span class="pre">url_defaults()</span></tt></a> function that adds the parameters
automatically again that were removed that way.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.url_defaults">
<tt class="descname">url_defaults</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.Flask.url_defaults" title="Permalink to this definition">¶</a></dt>
<dd><p>Callback function for URL defaults for all view functions of the
application.  It&#8217;s called with the endpoint and values and should
update the values passed in place.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.url_map">
<tt class="descname">url_map</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.url_map" title="Permalink to this definition">¶</a></dt>
<dd><p>The <a class="reference external" href="http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Map" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">Map</span></tt></a> for this instance.  You can use
this to change the routing converters after the class was created
but before any routes are connected.  Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">werkzeug.routing</span> <span class="kn">import</span> <span class="n">BaseConverter</span>

<span class="k">class</span> <span class="nc">ListConverter</span><span class="p">(</span><span class="n">BaseConverter</span><span class="p">):</span>
    <span class="k">def</span> <span class="nf">to_python</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">value</span><span class="p">):</span>
        <span class="k">return</span> <span class="n">value</span><span class="o">.</span><span class="n">split</span><span class="p">(</span><span class="s">&#39;,&#39;</span><span class="p">)</span>
    <span class="k">def</span> <span class="nf">to_url</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">values</span><span class="p">):</span>
        <span class="k">return</span> <span class="s">&#39;,&#39;</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">BaseConverter</span><span class="o">.</span><span class="n">to_url</span><span class="p">(</span><span class="n">value</span><span class="p">)</span>
                        <span class="k">for</span> <span class="n">value</span> <span class="ow">in</span> <span class="n">values</span><span class="p">)</span>

<span class="n">app</span> <span class="o">=</span> <span class="n">Flask</span><span class="p">(</span><span class="n">__name__</span><span class="p">)</span>
<span class="n">app</span><span class="o">.</span><span class="n">url_map</span><span class="o">.</span><span class="n">converters</span><span class="p">[</span><span class="s">&#39;list&#39;</span><span class="p">]</span> <span class="o">=</span> <span class="n">ListConverter</span>
</pre></div>
</div>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.url_rule_class">
<tt class="descname">url_rule_class</tt><a class="headerlink" href="#flask.Flask.url_rule_class" title="Permalink to this definition">¶</a></dt>
<dd><p>The rule object to use for URL rules created.  This is used by
<a class="reference internal" href="#flask.Flask.add_url_rule" title="flask.Flask.add_url_rule"><tt class="xref py py-meth docutils literal"><span class="pre">add_url_rule()</span></tt></a>.  Defaults to <a class="reference external" href="http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Rule" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">werkzeug.routing.Rule</span></tt></a>.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
<p>alias of <tt class="xref py py-class docutils literal"><span class="pre">Rule</span></tt></p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.url_value_preprocessor">
<tt class="descname">url_value_preprocessor</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.Flask.url_value_preprocessor" title="Permalink to this definition">¶</a></dt>
<dd><p>Registers a function as URL value preprocessor for all view
functions of the application.  It&#8217;s called before the view functions
are called and can modify the url values provided.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.url_value_preprocessors">
<tt class="descname">url_value_preprocessors</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.url_value_preprocessors" title="Permalink to this definition">¶</a></dt>
<dd><p>A dictionary with lists of functions that can be used as URL
value processor functions.  Whenever a URL is built these functions
are called to modify the dictionary of values in place.  The key
<cite>None</cite> here is used for application wide
callbacks, otherwise the key is the name of the blueprint.
Each of these functions has the chance to modify the dictionary</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.use_x_sendfile">
<tt class="descname">use_x_sendfile</tt><a class="headerlink" href="#flask.Flask.use_x_sendfile" title="Permalink to this definition">¶</a></dt>
<dd><p>Enable this if you want to use the X-Sendfile feature.  Keep in
mind that the server has to support this.  This only affects files
sent with the <a class="reference internal" href="#flask.send_file" title="flask.send_file"><tt class="xref py py-func docutils literal"><span class="pre">send_file()</span></tt></a> method.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.2.</span></p>
<p>This attribute can also be configured from the config with the
<cite>USE_X_SENDFILE</cite> configuration key.  Defaults to <cite>False</cite>.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Flask.view_functions">
<tt class="descname">view_functions</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Flask.view_functions" title="Permalink to this definition">¶</a></dt>
<dd><p>A dictionary of all view functions registered.  The keys will
be function names which are also used to generate URLs and
the values are the function objects themselves.
To register a view function, use the <a class="reference internal" href="#flask.Flask.route" title="flask.Flask.route"><tt class="xref py py-meth docutils literal"><span class="pre">route()</span></tt></a> decorator.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Flask.wsgi_app">
<tt class="descname">wsgi_app</tt><big>(</big><em>environ</em>, <em>start_response</em><big>)</big><a class="headerlink" href="#flask.Flask.wsgi_app" title="Permalink to this definition">¶</a></dt>
<dd><p>The actual WSGI application.  This is not implemented in
<cite>__call__</cite> so that middlewares can be applied without losing a
reference to the class.  So instead of doing this:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">app</span> <span class="o">=</span> <span class="n">MyMiddleware</span><span class="p">(</span><span class="n">app</span><span class="p">)</span>
</pre></div>
</div>
<p>It&#8217;s a better idea to do this instead:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">app</span><span class="o">.</span><span class="n">wsgi_app</span> <span class="o">=</span> <span class="n">MyMiddleware</span><span class="p">(</span><span class="n">app</span><span class="o">.</span><span class="n">wsgi_app</span><span class="p">)</span>
</pre></div>
</div>
<p>Then you still have the original application object around and
can continue to call methods on it.</p>
<p class="versionchanged">
<span class="versionmodified">Changed in version 0.7: </span>The behavior of the before and after request callbacks was changed
under error conditions and a new callback was added that will
always execute at the end of the request, independent on if an
error ocurred or not.  See <a class="reference internal" href="reqcontext.html#callbacks-and-errors"><em>Callbacks and Errors</em></a>.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>environ</strong> &#8211; a WSGI environment</li>
<li><strong>start_response</strong> &#8211; a callable accepting a status code,
a list of headers and an optional
exception context to start the response</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

</dd></dl>

</div>
<div class="section" id="blueprint-objects">
<h2>Blueprint Objects<a class="headerlink" href="#blueprint-objects" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="flask.Blueprint">
<em class="property">class </em><tt class="descclassname">flask.</tt><tt class="descname">Blueprint</tt><big>(</big><em>name</em>, <em>import_name</em>, <em>static_folder=None</em>, <em>static_url_path=None</em>, <em>template_folder=None</em>, <em>url_prefix=None</em>, <em>subdomain=None</em>, <em>url_defaults=None</em><big>)</big><a class="headerlink" href="#flask.Blueprint" title="Permalink to this definition">¶</a></dt>
<dd><p>Represents a blueprint.  A blueprint is an object that records
functions that will be called with the
<tt class="xref py py-class docutils literal"><span class="pre">BlueprintSetupState</span></tt> later to register functions
or other things on the main application.  See <a class="reference internal" href="blueprints.html#blueprints"><em>Modular Applications with Blueprints</em></a> for more
information.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
<dl class="method">
<dt id="flask.Blueprint.add_url_rule">
<tt class="descname">add_url_rule</tt><big>(</big><em>rule</em>, <em>endpoint=None</em>, <em>view_func=None</em>, <em>**options</em><big>)</big><a class="headerlink" href="#flask.Blueprint.add_url_rule" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#flask.Flask.add_url_rule" title="flask.Flask.add_url_rule"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.add_url_rule()</span></tt></a> but for a blueprint.  The endpoint for
the <a class="reference internal" href="#flask.url_for" title="flask.url_for"><tt class="xref py py-func docutils literal"><span class="pre">url_for()</span></tt></a> function is prefixed with the name of the blueprint.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.after_app_request">
<tt class="descname">after_app_request</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#flask.Blueprint.after_app_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#flask.Flask.after_request" title="flask.Flask.after_request"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.after_request()</span></tt></a> but for a blueprint.  Such a function
is executed after each request, even if outside of the blueprint.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.after_request">
<tt class="descname">after_request</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#flask.Blueprint.after_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#flask.Flask.after_request" title="flask.Flask.after_request"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.after_request()</span></tt></a> but for a blueprint.  This function
is only executed after each request that is handled by a function of
that blueprint.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.app_context_processor">
<tt class="descname">app_context_processor</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#flask.Blueprint.app_context_processor" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#flask.Flask.context_processor" title="flask.Flask.context_processor"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.context_processor()</span></tt></a> but for a blueprint.  Such a
function is executed each request, even if outside of the blueprint.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.app_errorhandler">
<tt class="descname">app_errorhandler</tt><big>(</big><em>code</em><big>)</big><a class="headerlink" href="#flask.Blueprint.app_errorhandler" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#flask.Flask.errorhandler" title="flask.Flask.errorhandler"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.errorhandler()</span></tt></a> but for a blueprint.  This
handler is used for all requests, even if outside of the blueprint.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.app_url_defaults">
<tt class="descname">app_url_defaults</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#flask.Blueprint.app_url_defaults" title="Permalink to this definition">¶</a></dt>
<dd><p>Same as <a class="reference internal" href="#flask.Blueprint.url_defaults" title="flask.Blueprint.url_defaults"><tt class="xref py py-meth docutils literal"><span class="pre">url_defaults()</span></tt></a> but application wide.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.app_url_value_preprocessor">
<tt class="descname">app_url_value_preprocessor</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#flask.Blueprint.app_url_value_preprocessor" title="Permalink to this definition">¶</a></dt>
<dd><p>Same as <a class="reference internal" href="#flask.Blueprint.url_value_preprocessor" title="flask.Blueprint.url_value_preprocessor"><tt class="xref py py-meth docutils literal"><span class="pre">url_value_preprocessor()</span></tt></a> but application wide.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.before_app_first_request">
<tt class="descname">before_app_first_request</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#flask.Blueprint.before_app_first_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#flask.Flask.before_first_request" title="flask.Flask.before_first_request"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.before_first_request()</span></tt></a>.  Such a function is
executed before the first request to the application.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.before_app_request">
<tt class="descname">before_app_request</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#flask.Blueprint.before_app_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#flask.Flask.before_request" title="flask.Flask.before_request"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.before_request()</span></tt></a>.  Such a function is executed
before each request, even if outside of a blueprint.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.before_request">
<tt class="descname">before_request</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#flask.Blueprint.before_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#flask.Flask.before_request" title="flask.Flask.before_request"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.before_request()</span></tt></a> but for a blueprint.  This function
is only executed before each request that is handled by a function of
that blueprint.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.context_processor">
<tt class="descname">context_processor</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#flask.Blueprint.context_processor" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#flask.Flask.context_processor" title="flask.Flask.context_processor"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.context_processor()</span></tt></a> but for a blueprint.  This
function is only executed for requests handled by a blueprint.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.endpoint">
<tt class="descname">endpoint</tt><big>(</big><em>endpoint</em><big>)</big><a class="headerlink" href="#flask.Blueprint.endpoint" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#flask.Flask.endpoint" title="flask.Flask.endpoint"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.endpoint()</span></tt></a> but for a blueprint.  This does not
prefix the endpoint with the blueprint name, this has to be done
explicitly by the user of this method.  If the endpoint is prefixed
with a <cite>.</cite> it will be registered to the current blueprint, otherwise
it&#8217;s an application independent endpoint.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.errorhandler">
<tt class="descname">errorhandler</tt><big>(</big><em>code_or_exception</em><big>)</big><a class="headerlink" href="#flask.Blueprint.errorhandler" title="Permalink to this definition">¶</a></dt>
<dd><p>Registers an error handler that becomes active for this blueprint
only.  Please be aware that routing does not happen local to a
blueprint so an error handler for 404 usually is not handled by
a blueprint unless it is caused inside a view function.  Another
special case is the 500 internal server error which is always looked
up from the application.</p>
<p>Otherwise works as the <a class="reference internal" href="#flask.Flask.errorhandler" title="flask.Flask.errorhandler"><tt class="xref py py-meth docutils literal"><span class="pre">errorhandler()</span></tt></a> decorator
of the <a class="reference internal" href="#flask.Flask" title="flask.Flask"><tt class="xref py py-class docutils literal"><span class="pre">Flask</span></tt></a> object.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Blueprint.has_static_folder">
<tt class="descname">has_static_folder</tt><a class="headerlink" href="#flask.Blueprint.has_static_folder" title="Permalink to this definition">¶</a></dt>
<dd><p>This is <cite>True</cite> if the package bound object&#8217;s container has a
folder named <tt class="docutils literal"><span class="pre">'static'</span></tt>.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.5.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Blueprint.jinja_loader">
<tt class="descname">jinja_loader</tt><a class="headerlink" href="#flask.Blueprint.jinja_loader" title="Permalink to this definition">¶</a></dt>
<dd><p>The Jinja loader for this package bound object.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.5.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.make_setup_state">
<tt class="descname">make_setup_state</tt><big>(</big><em>app</em>, <em>options</em>, <em>first_registration=False</em><big>)</big><a class="headerlink" href="#flask.Blueprint.make_setup_state" title="Permalink to this definition">¶</a></dt>
<dd><p>Creates an instance of <a class="reference internal" href="#flask.blueprints.BlueprintSetupState" title="flask.blueprints.BlueprintSetupState"><tt class="xref py py-meth docutils literal"><span class="pre">BlueprintSetupState()</span></tt></a>
object that is later passed to the register callback functions.
Subclasses can override this to return a subclass of the setup state.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.open_resource">
<tt class="descname">open_resource</tt><big>(</big><em>resource</em>, <em>mode='rb'</em><big>)</big><a class="headerlink" href="#flask.Blueprint.open_resource" title="Permalink to this definition">¶</a></dt>
<dd><p>Opens a resource from the application&#8217;s resource folder.  To see
how this works, consider the following folder structure:</p>
<div class="highlight-python"><pre>/myapplication.py
/schema.sql
/static
    /style.css
/templates
    /layout.html
    /index.html</pre>
</div>
<p>If you want to open the <cite>schema.sql</cite> file you would do the
following:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">with</span> <span class="n">app</span><span class="o">.</span><span class="n">open_resource</span><span class="p">(</span><span class="s">&#39;schema.sql&#39;</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span>
    <span class="n">contents</span> <span class="o">=</span> <span class="n">f</span><span class="o">.</span><span class="n">read</span><span class="p">()</span>
    <span class="n">do_something_with</span><span class="p">(</span><span class="n">contents</span><span class="p">)</span>
</pre></div>
</div>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>resource</strong> &#8211; the name of the resource.  To access resources within
subfolders use forward slashes as separator.</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.record">
<tt class="descname">record</tt><big>(</big><em>func</em><big>)</big><a class="headerlink" href="#flask.Blueprint.record" title="Permalink to this definition">¶</a></dt>
<dd><p>Registers a function that is called when the blueprint is
registered on the application.  This function is called with the
state as argument as returned by the <a class="reference internal" href="#flask.Blueprint.make_setup_state" title="flask.Blueprint.make_setup_state"><tt class="xref py py-meth docutils literal"><span class="pre">make_setup_state()</span></tt></a>
method.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.record_once">
<tt class="descname">record_once</tt><big>(</big><em>func</em><big>)</big><a class="headerlink" href="#flask.Blueprint.record_once" title="Permalink to this definition">¶</a></dt>
<dd><p>Works like <a class="reference internal" href="#flask.Blueprint.record" title="flask.Blueprint.record"><tt class="xref py py-meth docutils literal"><span class="pre">record()</span></tt></a> but wraps the function in another
function that will ensure the function is only called once.  If the
blueprint is registered a second time on the application, the
function passed is not called.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.register">
<tt class="descname">register</tt><big>(</big><em>app</em>, <em>options</em>, <em>first_registration=False</em><big>)</big><a class="headerlink" href="#flask.Blueprint.register" title="Permalink to this definition">¶</a></dt>
<dd><p>Called by <a class="reference internal" href="#flask.Flask.register_blueprint" title="flask.Flask.register_blueprint"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.register_blueprint()</span></tt></a> to register a blueprint
on the application.  This can be overridden to customize the register
behavior.  Keyword arguments from
<a class="reference internal" href="#flask.Flask.register_blueprint" title="flask.Flask.register_blueprint"><tt class="xref py py-func docutils literal"><span class="pre">register_blueprint()</span></tt></a> are directly forwarded to this
method in the <cite>options</cite> dictionary.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.route">
<tt class="descname">route</tt><big>(</big><em>rule</em>, <em>**options</em><big>)</big><a class="headerlink" href="#flask.Blueprint.route" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#flask.Flask.route" title="flask.Flask.route"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.route()</span></tt></a> but for a blueprint.  The endpoint for the
<a class="reference internal" href="#flask.url_for" title="flask.url_for"><tt class="xref py py-func docutils literal"><span class="pre">url_for()</span></tt></a> function is prefixed with the name of the blueprint.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.send_static_file">
<tt class="descname">send_static_file</tt><big>(</big><em>filename</em><big>)</big><a class="headerlink" href="#flask.Blueprint.send_static_file" title="Permalink to this definition">¶</a></dt>
<dd><p>Function used internally to send static files from the static
folder to the browser.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.5.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.teardown_app_request">
<tt class="descname">teardown_app_request</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#flask.Blueprint.teardown_app_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#flask.Flask.teardown_request" title="flask.Flask.teardown_request"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.teardown_request()</span></tt></a> but for a blueprint.  Such a
function is executed when tearing down each request, even if outside of
the blueprint.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.teardown_request">
<tt class="descname">teardown_request</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#flask.Blueprint.teardown_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <a class="reference internal" href="#flask.Flask.teardown_request" title="flask.Flask.teardown_request"><tt class="xref py py-meth docutils literal"><span class="pre">Flask.teardown_request()</span></tt></a> but for a blueprint.  This
function is only executed when tearing down requests handled by a
function of that blueprint.  Teardown request functions are executed
when the request context is popped, even when no actual request was
performed.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.url_defaults">
<tt class="descname">url_defaults</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#flask.Blueprint.url_defaults" title="Permalink to this definition">¶</a></dt>
<dd><p>Callback function for URL defaults for this blueprint.  It&#8217;s called
with the endpoint and values and should update the values passed
in place.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Blueprint.url_value_preprocessor">
<tt class="descname">url_value_preprocessor</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#flask.Blueprint.url_value_preprocessor" title="Permalink to this definition">¶</a></dt>
<dd><p>Registers a function as URL value preprocessor for this
blueprint.  It&#8217;s called before the view functions are called and
can modify the url values provided.</p>
</dd></dl>

</dd></dl>

</div>
<div class="section" id="incoming-request-data">
<h2>Incoming Request Data<a class="headerlink" href="#incoming-request-data" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="flask.Request">
<em class="property">class </em><tt class="descclassname">flask.</tt><tt class="descname">Request</tt><big>(</big><em>environ</em>, <em>populate_request=True</em>, <em>shallow=False</em><big>)</big><a class="headerlink" href="#flask.Request" title="Permalink to this definition">¶</a></dt>
<dd><p>The request object used by default in Flask.  Remembers the
matched endpoint and view arguments.</p>
<p>It is what ends up as <a class="reference internal" href="#flask.request" title="flask.request"><tt class="xref py py-class docutils literal"><span class="pre">request</span></tt></a>.  If you want to replace
the request object used you can subclass this and set
<a class="reference internal" href="#flask.Flask.request_class" title="flask.Flask.request_class"><tt class="xref py py-attr docutils literal"><span class="pre">request_class</span></tt></a> to your subclass.</p>
<p>The request object is a <a class="reference external" href="http://werkzeug.pocoo.org/docs/wrappers/#werkzeug.wrappers.Request" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">Request</span></tt></a> subclass and
provides all of the attributes Werkzeug defines plus a few Flask
specific ones.</p>
<dl class="attribute">
<dt id="flask.Request.form">
<tt class="descname">form</tt><a class="headerlink" href="#flask.Request.form" title="Permalink to this definition">¶</a></dt>
<dd><p>A <a class="reference external" href="http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.MultiDict" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">MultiDict</span></tt></a> with the parsed form data from <cite>POST</cite>
or <cite>PUT</cite> requests.  Please keep in mind that file uploads will not
end up here,  but instead in the <a class="reference internal" href="#flask.Request.files" title="flask.Request.files"><tt class="xref py py-attr docutils literal"><span class="pre">files</span></tt></a> attribute.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.args">
<tt class="descname">args</tt><a class="headerlink" href="#flask.Request.args" title="Permalink to this definition">¶</a></dt>
<dd><p>A <a class="reference external" href="http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.MultiDict" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">MultiDict</span></tt></a> with the parsed contents of the query
string.  (The part in the URL after the question mark).</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.values">
<tt class="descname">values</tt><a class="headerlink" href="#flask.Request.values" title="Permalink to this definition">¶</a></dt>
<dd><p>A <a class="reference external" href="http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.CombinedMultiDict" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">CombinedMultiDict</span></tt></a> with the contents of both
<a class="reference internal" href="#flask.Request.form" title="flask.Request.form"><tt class="xref py py-attr docutils literal"><span class="pre">form</span></tt></a> and <a class="reference internal" href="#flask.Request.args" title="flask.Request.args"><tt class="xref py py-attr docutils literal"><span class="pre">args</span></tt></a>.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.cookies">
<tt class="descname">cookies</tt><a class="headerlink" href="#flask.Request.cookies" title="Permalink to this definition">¶</a></dt>
<dd><p>A <a class="reference external" href="http://docs.python.org/dev/library/stdtypes.html#dict" title="(in Python v3.3)"><tt class="xref py py-class docutils literal"><span class="pre">dict</span></tt></a> with the contents of all cookies transmitted with
the request.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.stream">
<tt class="descname">stream</tt><a class="headerlink" href="#flask.Request.stream" title="Permalink to this definition">¶</a></dt>
<dd><p>If the incoming form data was not encoded with a known mimetype
the data is stored unmodified in this stream for consumption.  Most
of the time it is a better idea to use <a class="reference internal" href="#flask.Request.data" title="flask.Request.data"><tt class="xref py py-attr docutils literal"><span class="pre">data</span></tt></a> which will give
you that data as a string.  The stream only returns the data once.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.headers">
<tt class="descname">headers</tt><a class="headerlink" href="#flask.Request.headers" title="Permalink to this definition">¶</a></dt>
<dd><p>The incoming request headers as a dictionary like object.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.data">
<tt class="descname">data</tt><a class="headerlink" href="#flask.Request.data" title="Permalink to this definition">¶</a></dt>
<dd><p>Contains the incoming request data as string in case it came with
a mimetype Flask does not handle.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.files">
<tt class="descname">files</tt><a class="headerlink" href="#flask.Request.files" title="Permalink to this definition">¶</a></dt>
<dd><p>A <a class="reference external" href="http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.MultiDict" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">MultiDict</span></tt></a> with files uploaded as part of a
<cite>POST</cite> or <cite>PUT</cite> request.  Each file is stored as
<a class="reference external" href="http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.FileStorage" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">FileStorage</span></tt></a> object.  It basically behaves like a
standard file object you know from Python, with the difference that
it also has a <a class="reference external" href="http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.FileStorage.save" title="(in Werkzeug v0.7)"><tt class="xref py py-meth docutils literal"><span class="pre">save()</span></tt></a> function that can
store the file on the filesystem.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.environ">
<tt class="descname">environ</tt><a class="headerlink" href="#flask.Request.environ" title="Permalink to this definition">¶</a></dt>
<dd><p>The underlying WSGI environment.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.method">
<tt class="descname">method</tt><a class="headerlink" href="#flask.Request.method" title="Permalink to this definition">¶</a></dt>
<dd><p>The current request method (<tt class="docutils literal"><span class="pre">POST</span></tt>, <tt class="docutils literal"><span class="pre">GET</span></tt> etc.)</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.path">
<tt class="descname">path</tt><a class="headerlink" href="#flask.Request.path" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>

<dl class="attribute">
<dt id="flask.Request.script_root">
<tt class="descname">script_root</tt><a class="headerlink" href="#flask.Request.script_root" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>

<dl class="attribute">
<dt id="flask.Request.url">
<tt class="descname">url</tt><a class="headerlink" href="#flask.Request.url" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>

<dl class="attribute">
<dt id="flask.Request.base_url">
<tt class="descname">base_url</tt><a class="headerlink" href="#flask.Request.base_url" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>

<dl class="attribute">
<dt id="flask.Request.url_root">
<tt class="descname">url_root</tt><a class="headerlink" href="#flask.Request.url_root" title="Permalink to this definition">¶</a></dt>
<dd><p>Provides different ways to look at the current URL.  Imagine your
application is listening on the following URL:</p>
<div class="highlight-python"><pre>http://www.example.com/myapplication</pre>
</div>
<p>And a user requests the following URL:</p>
<div class="highlight-python"><pre>http://www.example.com/myapplication/page.html?x=y</pre>
</div>
<p>In this case the values of the above mentioned attributes would be
the following:</p>
<table border="1" class="docutils">
<colgroup>
<col width="19%" />
<col width="81%" />
</colgroup>
<tbody valign="top">
<tr class="row-odd"><td><cite>path</cite></td>
<td><tt class="docutils literal"><span class="pre">/page.html</span></tt></td>
</tr>
<tr class="row-even"><td><cite>script_root</cite></td>
<td><tt class="docutils literal"><span class="pre">/myapplication</span></tt></td>
</tr>
<tr class="row-odd"><td><cite>base_url</cite></td>
<td><tt class="docutils literal"><span class="pre">http://www.example.com/myapplication/page.html</span></tt></td>
</tr>
<tr class="row-even"><td><cite>url</cite></td>
<td><tt class="docutils literal"><span class="pre">http://www.example.com/myapplication/page.html?x=y</span></tt></td>
</tr>
<tr class="row-odd"><td><cite>url_root</cite></td>
<td><tt class="docutils literal"><span class="pre">http://www.example.com/myapplication/</span></tt></td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.is_xhr">
<tt class="descname">is_xhr</tt><a class="headerlink" href="#flask.Request.is_xhr" title="Permalink to this definition">¶</a></dt>
<dd><p><cite>True</cite> if the request was triggered via a JavaScript
<cite>XMLHttpRequest</cite>. This only works with libraries that support the
<tt class="docutils literal"><span class="pre">X-Requested-With</span></tt> header and set it to <cite>XMLHttpRequest</cite>.
Libraries that do that are prototype, jQuery and Mochikit and
probably some more.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.blueprint">
<tt class="descname">blueprint</tt><a class="headerlink" href="#flask.Request.blueprint" title="Permalink to this definition">¶</a></dt>
<dd><p>The name of the current blueprint</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.endpoint">
<tt class="descname">endpoint</tt><a class="headerlink" href="#flask.Request.endpoint" title="Permalink to this definition">¶</a></dt>
<dd><p>The endpoint that matched the request.  This in combination with
<a class="reference internal" href="#flask.Request.view_args" title="flask.Request.view_args"><tt class="xref py py-attr docutils literal"><span class="pre">view_args</span></tt></a> can be used to reconstruct the same or a
modified URL.  If an exception happened when matching, this will
be <cite>None</cite>.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.json">
<tt class="descname">json</tt><a class="headerlink" href="#flask.Request.json" title="Permalink to this definition">¶</a></dt>
<dd><p>If the mimetype is <cite>application/json</cite> this will contain the
parsed JSON data.  Otherwise this will be <cite>None</cite>.</p>
<p>This requires Python 2.6 or an installed version of simplejson.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.max_content_length">
<tt class="descname">max_content_length</tt><a class="headerlink" href="#flask.Request.max_content_length" title="Permalink to this definition">¶</a></dt>
<dd><p>Read-only view of the <cite>MAX_CONTENT_LENGTH</cite> config key.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.module">
<tt class="descname">module</tt><a class="headerlink" href="#flask.Request.module" title="Permalink to this definition">¶</a></dt>
<dd><p>The name of the current module if the request was dispatched
to an actual module.  This is deprecated functionality, use blueprints
instead.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Request.on_json_loading_failed">
<tt class="descname">on_json_loading_failed</tt><big>(</big><em>e</em><big>)</big><a class="headerlink" href="#flask.Request.on_json_loading_failed" title="Permalink to this definition">¶</a></dt>
<dd><p>Called if decoding of the JSON data failed.  The return value of
this method is used by <a class="reference internal" href="#flask.json" title="flask.json"><tt class="xref py py-attr docutils literal"><span class="pre">json</span></tt></a> when an error ocurred.  The
default implementation raises a <tt class="xref py py-class docutils literal"><span class="pre">BadRequest</span></tt>.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.routing_exception">
<tt class="descname">routing_exception</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Request.routing_exception" title="Permalink to this definition">¶</a></dt>
<dd><p>if matching the URL failed, this is the exception that will be
raised / was raised as part of the request handling.  This is
usually a <a class="reference external" href="http://werkzeug.pocoo.org/docs/exceptions/#werkzeug.exceptions.NotFound" title="(in Werkzeug v0.7)"><tt class="xref py py-exc docutils literal"><span class="pre">NotFound</span></tt></a> exception or
something similar.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.url_rule">
<tt class="descname">url_rule</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Request.url_rule" title="Permalink to this definition">¶</a></dt>
<dd><p>the internal URL rule that matched the request.  This can be
useful to inspect which methods are allowed for the URL from
a before/after handler (<tt class="docutils literal"><span class="pre">request.url_rule.methods</span></tt>) etc.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.6.</span></p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Request.view_args">
<tt class="descname">view_args</tt><em class="property"> = None</em><a class="headerlink" href="#flask.Request.view_args" title="Permalink to this definition">¶</a></dt>
<dd><p>a dict of view arguments that matched the request.  If an exception
happened when matching, this will be <cite>None</cite>.</p>
</dd></dl>

</dd></dl>

<dl class="class">
<dt id="flask.request">
<em class="property">class </em><tt class="descclassname">flask.</tt><tt class="descname">request</tt><a class="headerlink" href="#flask.request" title="Permalink to this definition">¶</a></dt>
<dd><p>To access incoming request data, you can use the global <cite>request</cite>
object.  Flask parses incoming request data for you and gives you
access to it through that global object.  Internally Flask makes
sure that you always get the correct data for the active thread if you
are in a multithreaded environment.</p>
<p>This is a proxy.  See <a class="reference internal" href="reqcontext.html#notes-on-proxies"><em>Notes On Proxies</em></a> for more information.</p>
<p>The request object is an instance of a <a class="reference external" href="http://werkzeug.pocoo.org/docs/wrappers/#werkzeug.wrappers.Request" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">Request</span></tt></a>
subclass and provides all of the attributes Werkzeug defines.  This
just shows a quick overview of the most important ones.</p>
</dd></dl>

</div>
<div class="section" id="response-objects">
<h2>Response Objects<a class="headerlink" href="#response-objects" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="flask.Response">
<em class="property">class </em><tt class="descclassname">flask.</tt><tt class="descname">Response</tt><big>(</big><em>response=None</em>, <em>status=None</em>, <em>headers=None</em>, <em>mimetype=None</em>, <em>content_type=None</em>, <em>direct_passthrough=False</em><big>)</big><a class="headerlink" href="#flask.Response" title="Permalink to this definition">¶</a></dt>
<dd><p>The response object that is used by default in Flask.  Works like the
response object from Werkzeug but is set to have an HTML mimetype by
default.  Quite often you don&#8217;t have to create this object yourself because
<a class="reference internal" href="#flask.Flask.make_response" title="flask.Flask.make_response"><tt class="xref py py-meth docutils literal"><span class="pre">make_response()</span></tt></a> will take care of that for you.</p>
<p>If you want to replace the response object used you can subclass this and
set <a class="reference internal" href="#flask.Flask.response_class" title="flask.Flask.response_class"><tt class="xref py py-attr docutils literal"><span class="pre">response_class</span></tt></a> to your subclass.</p>
<dl class="attribute">
<dt id="flask.Response.headers">
<tt class="descname">headers</tt><a class="headerlink" href="#flask.Response.headers" title="Permalink to this definition">¶</a></dt>
<dd><p>A <tt class="xref py py-class docutils literal"><span class="pre">Headers</span></tt> object representing the response headers.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Response.status_code">
<tt class="descname">status_code</tt><a class="headerlink" href="#flask.Response.status_code" title="Permalink to this definition">¶</a></dt>
<dd><p>The response status as integer.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Response.set_cookie">
<tt class="descname">set_cookie</tt><big>(</big><em>key</em>, <em>value=''</em>, <em>max_age=None</em>, <em>expires=None</em>, <em>path='/'</em>, <em>domain=None</em>, <em>secure=None</em>, <em>httponly=False</em><big>)</big><a class="headerlink" href="#flask.Response.set_cookie" title="Permalink to this definition">¶</a></dt>
<dd><p>Sets a cookie. The parameters are the same as in the cookie <cite>Morsel</cite>
object in the Python standard library but it accepts unicode data, too.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>key</strong> &#8211; the key (name) of the cookie to be set.</li>
<li><strong>value</strong> &#8211; the value of the cookie.</li>
<li><strong>max_age</strong> &#8211; should be a number of seconds, or <cite>None</cite> (default) if
the cookie should last only as long as the client&#8217;s
browser session.</li>
<li><strong>expires</strong> &#8211; should be a <cite>datetime</cite> object or UNIX timestamp.</li>
<li><strong>domain</strong> &#8211; if you want to set a cross-domain cookie.  For example,
<tt class="docutils literal"><span class="pre">domain=&quot;.example.com&quot;</span></tt> will set a cookie that is
readable by the domain <tt class="docutils literal"><span class="pre">www.example.com</span></tt>,
<tt class="docutils literal"><span class="pre">foo.example.com</span></tt> etc.  Otherwise, a cookie will only
be readable by the domain that set it.</li>
<li><strong>path</strong> &#8211; limits the cookie to a given path, per default it will
span the whole domain.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="attribute">
<dt id="flask.Response.data">
<tt class="descname">data</tt><a class="headerlink" href="#flask.Response.data" title="Permalink to this definition">¶</a></dt>
<dd><p>The string representation of the request body.  Whenever you access
this property the request iterable is encoded and flattened.  This
can lead to unwanted behavior if you stream big data.</p>
<p>This behavior can be disabled by setting
<tt class="xref py py-attr docutils literal"><span class="pre">implicit_sequence_conversion</span></tt> to <cite>False</cite>.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.Response.mimetype">
<tt class="descname">mimetype</tt><a class="headerlink" href="#flask.Response.mimetype" title="Permalink to this definition">¶</a></dt>
<dd><p>The mimetype (content type without charset etc.)</p>
</dd></dl>

</dd></dl>

</div>
<div class="section" id="sessions">
<h2>Sessions<a class="headerlink" href="#sessions" title="Permalink to this headline">¶</a></h2>
<p>If you have the <a class="reference internal" href="#flask.Flask.secret_key" title="flask.Flask.secret_key"><tt class="xref py py-attr docutils literal"><span class="pre">Flask.secret_key</span></tt></a> set you can use sessions in Flask
applications.  A session basically makes it possible to remember
information from one request to another.  The way Flask does this is by
using a signed cookie.  So the user can look at the session contents, but
not modify it unless they know the secret key, so make sure to set that
to something complex and unguessable.</p>
<p>To access the current session you can use the <a class="reference internal" href="#flask.session" title="flask.session"><tt class="xref py py-class docutils literal"><span class="pre">session</span></tt></a> object:</p>
<dl class="class">
<dt id="flask.session">
<em class="property">class </em><tt class="descclassname">flask.</tt><tt class="descname">session</tt><a class="headerlink" href="#flask.session" title="Permalink to this definition">¶</a></dt>
<dd><p>The session object works pretty much like an ordinary dict, with the
difference that it keeps track on modifications.</p>
<p>This is a proxy.  See <a class="reference internal" href="reqcontext.html#notes-on-proxies"><em>Notes On Proxies</em></a> for more information.</p>
<p>The following attributes are interesting:</p>
<dl class="attribute">
<dt id="flask.session.new">
<tt class="descname">new</tt><a class="headerlink" href="#flask.session.new" title="Permalink to this definition">¶</a></dt>
<dd><p><cite>True</cite> if the session is new, <cite>False</cite> otherwise.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.session.modified">
<tt class="descname">modified</tt><a class="headerlink" href="#flask.session.modified" title="Permalink to this definition">¶</a></dt>
<dd><p><cite>True</cite> if the session object detected a modification.  Be advised
that modifications on mutable structures are not picked up
automatically, in that situation you have to explicitly set the
attribute to <cite>True</cite> yourself.  Here an example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="c"># this change is not picked up because a mutable object (here</span>
<span class="c"># a list) is changed.</span>
<span class="n">session</span><span class="p">[</span><span class="s">&#39;objects&#39;</span><span class="p">]</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="mi">42</span><span class="p">)</span>
<span class="c"># so mark it as modified yourself</span>
<span class="n">session</span><span class="o">.</span><span class="n">modified</span> <span class="o">=</span> <span class="bp">True</span>
</pre></div>
</div>
</dd></dl>

<dl class="attribute">
<dt id="flask.session.permanent">
<tt class="descname">permanent</tt><a class="headerlink" href="#flask.session.permanent" title="Permalink to this definition">¶</a></dt>
<dd><p>If set to <cite>True</cite> the session lives for
<a class="reference internal" href="#flask.Flask.permanent_session_lifetime" title="flask.Flask.permanent_session_lifetime"><tt class="xref py py-attr docutils literal"><span class="pre">permanent_session_lifetime</span></tt></a> seconds.  The
default is 31 days.  If set to <cite>False</cite> (which is the default) the
session will be deleted when the user closes the browser.</p>
</dd></dl>

</dd></dl>

</div>
<div class="section" id="session-interface">
<h2>Session Interface<a class="headerlink" href="#session-interface" title="Permalink to this headline">¶</a></h2>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
<p>The session interface provides a simple way to replace the session
implementation that Flask is using.</p>
<dl class="class">
<dt id="flask.sessions.SessionInterface">
<em class="property">class </em><tt class="descclassname">flask.sessions.</tt><tt class="descname">SessionInterface</tt><a class="headerlink" href="#flask.sessions.SessionInterface" title="Permalink to this definition">¶</a></dt>
<dd><p>The basic interface you have to implement in order to replace the
default session interface which uses werkzeug&#8217;s securecookie
implementation.  The only methods you have to implement are
<a class="reference internal" href="#flask.sessions.SessionInterface.open_session" title="flask.sessions.SessionInterface.open_session"><tt class="xref py py-meth docutils literal"><span class="pre">open_session()</span></tt></a> and <a class="reference internal" href="#flask.sessions.SessionInterface.save_session" title="flask.sessions.SessionInterface.save_session"><tt class="xref py py-meth docutils literal"><span class="pre">save_session()</span></tt></a>, the others have
useful defaults which you don&#8217;t need to change.</p>
<p>The session object returned by the <a class="reference internal" href="#flask.sessions.SessionInterface.open_session" title="flask.sessions.SessionInterface.open_session"><tt class="xref py py-meth docutils literal"><span class="pre">open_session()</span></tt></a> method has to
provide a dictionary like interface plus the properties and methods
from the <a class="reference internal" href="#flask.sessions.SessionMixin" title="flask.sessions.SessionMixin"><tt class="xref py py-class docutils literal"><span class="pre">SessionMixin</span></tt></a>.  We recommend just subclassing a dict
and adding that mixin:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">class</span> <span class="nc">Session</span><span class="p">(</span><span class="nb">dict</span><span class="p">,</span> <span class="n">SessionMixin</span><span class="p">):</span>
    <span class="k">pass</span>
</pre></div>
</div>
<p>If <a class="reference internal" href="#flask.sessions.SessionInterface.open_session" title="flask.sessions.SessionInterface.open_session"><tt class="xref py py-meth docutils literal"><span class="pre">open_session()</span></tt></a> returns <cite>None</cite> Flask will call into
<a class="reference internal" href="#flask.sessions.SessionInterface.make_null_session" title="flask.sessions.SessionInterface.make_null_session"><tt class="xref py py-meth docutils literal"><span class="pre">make_null_session()</span></tt></a> to create a session that acts as replacement
if the session support cannot work because some requirement is not
fulfilled.  The default <a class="reference internal" href="#flask.sessions.NullSession" title="flask.sessions.NullSession"><tt class="xref py py-class docutils literal"><span class="pre">NullSession</span></tt></a> class that is created
will complain that the secret key was not set.</p>
<p>To replace the session interface on an application all you have to do
is to assign <a class="reference internal" href="#flask.Flask.session_interface" title="flask.Flask.session_interface"><tt class="xref py py-attr docutils literal"><span class="pre">flask.Flask.session_interface</span></tt></a>:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">app</span> <span class="o">=</span> <span class="n">Flask</span><span class="p">(</span><span class="n">__name__</span><span class="p">)</span>
<span class="n">app</span><span class="o">.</span><span class="n">session_interface</span> <span class="o">=</span> <span class="n">MySessionInterface</span><span class="p">()</span>
</pre></div>
</div>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
<dl class="method">
<dt id="flask.sessions.SessionInterface.get_cookie_domain">
<tt class="descname">get_cookie_domain</tt><big>(</big><em>app</em><big>)</big><a class="headerlink" href="#flask.sessions.SessionInterface.get_cookie_domain" title="Permalink to this definition">¶</a></dt>
<dd><p>Helpful helper method that returns the cookie domain that should
be used for the session cookie if session cookies are used.</p>
</dd></dl>

<dl class="method">
<dt id="flask.sessions.SessionInterface.get_cookie_httponly">
<tt class="descname">get_cookie_httponly</tt><big>(</big><em>app</em><big>)</big><a class="headerlink" href="#flask.sessions.SessionInterface.get_cookie_httponly" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns True if the session cookie should be httponly.  This
currently just returns the value of the <tt class="docutils literal"><span class="pre">SESSION_COOKIE_HTTPONLY</span></tt>
config var.</p>
</dd></dl>

<dl class="method">
<dt id="flask.sessions.SessionInterface.get_cookie_path">
<tt class="descname">get_cookie_path</tt><big>(</big><em>app</em><big>)</big><a class="headerlink" href="#flask.sessions.SessionInterface.get_cookie_path" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns the path for which the cookie should be valid.  The
default implementation uses the value from the SESSION_COOKIE_PATH``
config var if it&#8217;s set, and falls back to <tt class="docutils literal"><span class="pre">APPLICATION_ROOT</span></tt> or
uses <tt class="docutils literal"><span class="pre">/</span></tt> if it&#8217;s <cite>None</cite>.</p>
</dd></dl>

<dl class="method">
<dt id="flask.sessions.SessionInterface.get_cookie_secure">
<tt class="descname">get_cookie_secure</tt><big>(</big><em>app</em><big>)</big><a class="headerlink" href="#flask.sessions.SessionInterface.get_cookie_secure" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns True if the cookie should be secure.  This currently
just returns the value of the <tt class="docutils literal"><span class="pre">SESSION_COOKIE_SECURE</span></tt> setting.</p>
</dd></dl>

<dl class="method">
<dt id="flask.sessions.SessionInterface.get_expiration_time">
<tt class="descname">get_expiration_time</tt><big>(</big><em>app</em>, <em>session</em><big>)</big><a class="headerlink" href="#flask.sessions.SessionInterface.get_expiration_time" title="Permalink to this definition">¶</a></dt>
<dd><p>A helper method that returns an expiration date for the session
or <cite>None</cite> if the session is linked to the browser session.  The
default implementation returns now + the permanent session
lifetime configured on the application.</p>
</dd></dl>

<dl class="method">
<dt id="flask.sessions.SessionInterface.is_null_session">
<tt class="descname">is_null_session</tt><big>(</big><em>obj</em><big>)</big><a class="headerlink" href="#flask.sessions.SessionInterface.is_null_session" title="Permalink to this definition">¶</a></dt>
<dd><p>Checks if a given object is a null session.  Null sessions are
not asked to be saved.</p>
<p>This checks if the object is an instance of <a class="reference internal" href="#flask.sessions.SessionInterface.null_session_class" title="flask.sessions.SessionInterface.null_session_class"><tt class="xref py py-attr docutils literal"><span class="pre">null_session_class</span></tt></a>
by default.</p>
</dd></dl>

<dl class="method">
<dt id="flask.sessions.SessionInterface.make_null_session">
<tt class="descname">make_null_session</tt><big>(</big><em>app</em><big>)</big><a class="headerlink" href="#flask.sessions.SessionInterface.make_null_session" title="Permalink to this definition">¶</a></dt>
<dd><p>Creates a null session which acts as a replacement object if the
real session support could not be loaded due to a configuration
error.  This mainly aids the user experience because the job of the
null session is to still support lookup without complaining but
modifications are answered with a helpful error message of what
failed.</p>
<p>This creates an instance of <a class="reference internal" href="#flask.sessions.SessionInterface.null_session_class" title="flask.sessions.SessionInterface.null_session_class"><tt class="xref py py-attr docutils literal"><span class="pre">null_session_class</span></tt></a> by default.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.sessions.SessionInterface.null_session_class">
<tt class="descname">null_session_class</tt><a class="headerlink" href="#flask.sessions.SessionInterface.null_session_class" title="Permalink to this definition">¶</a></dt>
<dd><p><a class="reference internal" href="#flask.sessions.SessionInterface.make_null_session" title="flask.sessions.SessionInterface.make_null_session"><tt class="xref py py-meth docutils literal"><span class="pre">make_null_session()</span></tt></a> will look here for the class that should
be created when a null session is requested.  Likewise the
<a class="reference internal" href="#flask.sessions.SessionInterface.is_null_session" title="flask.sessions.SessionInterface.is_null_session"><tt class="xref py py-meth docutils literal"><span class="pre">is_null_session()</span></tt></a> method will perform a typecheck against
this type.</p>
<p>alias of <a class="reference internal" href="#flask.sessions.NullSession" title="flask.sessions.NullSession"><tt class="xref py py-class docutils literal"><span class="pre">NullSession</span></tt></a></p>
</dd></dl>

<dl class="method">
<dt id="flask.sessions.SessionInterface.open_session">
<tt class="descname">open_session</tt><big>(</big><em>app</em>, <em>request</em><big>)</big><a class="headerlink" href="#flask.sessions.SessionInterface.open_session" title="Permalink to this definition">¶</a></dt>
<dd><p>This method has to be implemented and must either return <cite>None</cite>
in case the loading failed because of a configuration error or an
instance of a session object which implements a dictionary like
interface + the methods and attributes on <a class="reference internal" href="#flask.sessions.SessionMixin" title="flask.sessions.SessionMixin"><tt class="xref py py-class docutils literal"><span class="pre">SessionMixin</span></tt></a>.</p>
</dd></dl>

<dl class="method">
<dt id="flask.sessions.SessionInterface.save_session">
<tt class="descname">save_session</tt><big>(</big><em>app</em>, <em>session</em>, <em>response</em><big>)</big><a class="headerlink" href="#flask.sessions.SessionInterface.save_session" title="Permalink to this definition">¶</a></dt>
<dd><p>This is called for actual sessions returned by <a class="reference internal" href="#flask.sessions.SessionInterface.open_session" title="flask.sessions.SessionInterface.open_session"><tt class="xref py py-meth docutils literal"><span class="pre">open_session()</span></tt></a>
at the end of the request.  This is still called during a request
context so if you absolutely need access to the request you can do
that.</p>
</dd></dl>

</dd></dl>

<dl class="class">
<dt id="flask.sessions.SecureCookieSessionInterface">
<em class="property">class </em><tt class="descclassname">flask.sessions.</tt><tt class="descname">SecureCookieSessionInterface</tt><a class="headerlink" href="#flask.sessions.SecureCookieSessionInterface" title="Permalink to this definition">¶</a></dt>
<dd><p>The cookie session interface that uses the Werkzeug securecookie
as client side session backend.</p>
<dl class="attribute">
<dt id="flask.sessions.SecureCookieSessionInterface.session_class">
<tt class="descname">session_class</tt><a class="headerlink" href="#flask.sessions.SecureCookieSessionInterface.session_class" title="Permalink to this definition">¶</a></dt>
<dd><p>alias of <tt class="xref py py-class docutils literal"><span class="pre">SecureCookieSession</span></tt></p>
</dd></dl>

</dd></dl>

<dl class="class">
<dt id="flask.sessions.NullSession">
<em class="property">class </em><tt class="descclassname">flask.sessions.</tt><tt class="descname">NullSession</tt><big>(</big><em>data=None</em>, <em>secret_key=None</em>, <em>new=True</em><big>)</big><a class="headerlink" href="#flask.sessions.NullSession" title="Permalink to this definition">¶</a></dt>
<dd><p>Class used to generate nicer error messages if sessions are not
available.  Will still allow read-only access to the empty session
but fail on setting.</p>
</dd></dl>

<dl class="class">
<dt id="flask.sessions.SessionMixin">
<em class="property">class </em><tt class="descclassname">flask.sessions.</tt><tt class="descname">SessionMixin</tt><a class="headerlink" href="#flask.sessions.SessionMixin" title="Permalink to this definition">¶</a></dt>
<dd><p>Expands a basic dictionary with an accessors that are expected
by Flask extensions and users for the session.</p>
<dl class="attribute">
<dt id="flask.sessions.SessionMixin.modified">
<tt class="descname">modified</tt><em class="property"> = True</em><a class="headerlink" href="#flask.sessions.SessionMixin.modified" title="Permalink to this definition">¶</a></dt>
<dd><p>for some backends this will always be <cite>True</cite>, but some backends will
default this to false and detect changes in the dictionary for as
long as changes do not happen on mutable structures in the session.
The default mixin implementation just hardcodes <cite>True</cite> in.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.sessions.SessionMixin.new">
<tt class="descname">new</tt><em class="property"> = False</em><a class="headerlink" href="#flask.sessions.SessionMixin.new" title="Permalink to this definition">¶</a></dt>
<dd><p>some session backends can tell you if a session is new, but that is
not necessarily guaranteed.  Use with caution.  The default mixin
implementation just hardcodes <cite>False</cite> in.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.sessions.SessionMixin.permanent">
<tt class="descname">permanent</tt><a class="headerlink" href="#flask.sessions.SessionMixin.permanent" title="Permalink to this definition">¶</a></dt>
<dd><p>this reflects the <tt class="docutils literal"><span class="pre">'_permanent'</span></tt> key in the dict.</p>
</dd></dl>

</dd></dl>

<div class="admonition-notice admonition ">
<p class="first admonition-title">Notice</p>
<p class="last">The <tt class="docutils literal"><span class="pre">PERMANENT_SESSION_LIFETIME</span></tt> config key can also be an integer
starting with Flask 0.8.  Either catch this down yourself or use
the <a class="reference internal" href="#flask.Flask.permanent_session_lifetime" title="flask.Flask.permanent_session_lifetime"><tt class="xref py py-attr docutils literal"><span class="pre">permanent_session_lifetime</span></tt></a> attribute on the
app which converts the result to an integer automatically.</p>
</div>
</div>
<div class="section" id="test-client">
<h2>Test Client<a class="headerlink" href="#test-client" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="flask.testing.FlaskClient">
<em class="property">class </em><tt class="descclassname">flask.testing.</tt><tt class="descname">FlaskClient</tt><big>(</big><em>application</em>, <em>response_wrapper=None</em>, <em>use_cookies=True</em>, <em>allow_subdomain_redirects=False</em><big>)</big><a class="headerlink" href="#flask.testing.FlaskClient" title="Permalink to this definition">¶</a></dt>
<dd><p>Works like a regular Werkzeug test client but has some knowledge about
how Flask works to defer the cleanup of the request context stack to the
end of a with body when used in a with statement.  For general information
about how to use this class refer to <a class="reference external" href="http://werkzeug.pocoo.org/docs/test/#werkzeug.test.Client" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">werkzeug.test.Client</span></tt></a>.</p>
<p>Basic usage is outlined in the <a class="reference internal" href="testing.html#testing"><em>Testing Flask Applications</em></a> chapter.</p>
<dl class="method">
<dt id="flask.testing.FlaskClient.session_transaction">
<tt class="descname">session_transaction</tt><big>(</big><em>*args</em>, <em>**kwds</em><big>)</big><a class="headerlink" href="#flask.testing.FlaskClient.session_transaction" title="Permalink to this definition">¶</a></dt>
<dd><p>When used in combination with a with statement this opens a
session transaction.  This can be used to modify the session that
the test client uses.  Once the with block is left the session is
stored back.</p>
<blockquote>
<div><dl class="docutils">
<dt>with client.session_transaction() as session:</dt>
<dd>session[&#8216;value&#8217;] = 42</dd>
</dl>
</div></blockquote>
<p>Internally this is implemented by going through a temporary test
request context and since session handling could depend on
request variables this function accepts the same arguments as
<a class="reference internal" href="#flask.Flask.test_request_context" title="flask.Flask.test_request_context"><tt class="xref py py-meth docutils literal"><span class="pre">test_request_context()</span></tt></a> which are directly
passed through.</p>
</dd></dl>

</dd></dl>

</div>
<div class="section" id="application-globals">
<h2>Application Globals<a class="headerlink" href="#application-globals" title="Permalink to this headline">¶</a></h2>
<p>To share data that is valid for one request only from one function to
another, a global variable is not good enough because it would break in
threaded environments.  Flask provides you with a special object that
ensures it is only valid for the active request and that will return
different values for each request.  In a nutshell: it does the right
thing, like it does for <a class="reference internal" href="#flask.request" title="flask.request"><tt class="xref py py-class docutils literal"><span class="pre">request</span></tt></a> and <a class="reference internal" href="#flask.session" title="flask.session"><tt class="xref py py-class docutils literal"><span class="pre">session</span></tt></a>.</p>
<dl class="data">
<dt id="flask.g">
<tt class="descclassname">flask.</tt><tt class="descname">g</tt><a class="headerlink" href="#flask.g" title="Permalink to this definition">¶</a></dt>
<dd><p>Just store on this whatever you want.  For example a database
connection or the user that is currently logged in.</p>
<p>This is a proxy.  See <a class="reference internal" href="reqcontext.html#notes-on-proxies"><em>Notes On Proxies</em></a> for more information.</p>
</dd></dl>

</div>
<div class="section" id="useful-functions-and-classes">
<h2>Useful Functions and Classes<a class="headerlink" href="#useful-functions-and-classes" title="Permalink to this headline">¶</a></h2>
<dl class="data">
<dt id="flask.current_app">
<tt class="descclassname">flask.</tt><tt class="descname">current_app</tt><a class="headerlink" href="#flask.current_app" title="Permalink to this definition">¶</a></dt>
<dd><p>Points to the application handling the request.  This is useful for
extensions that want to support multiple applications running side
by side.</p>
<p>This is a proxy.  See <a class="reference internal" href="reqcontext.html#notes-on-proxies"><em>Notes On Proxies</em></a> for more information.</p>
</dd></dl>

<dl class="function">
<dt id="flask.has_request_context">
<tt class="descclassname">flask.</tt><tt class="descname">has_request_context</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.has_request_context" title="Permalink to this definition">¶</a></dt>
<dd><p>If you have code that wants to test if a request context is there or
not this function can be used.  For instance if you want to take advantage
of request information is it&#8217;s available but fail silently if the request
object is unavailable.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">class</span> <span class="nc">User</span><span class="p">(</span><span class="n">db</span><span class="o">.</span><span class="n">Model</span><span class="p">):</span>

    <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">username</span><span class="p">,</span> <span class="n">remote_addr</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
        <span class="bp">self</span><span class="o">.</span><span class="n">username</span> <span class="o">=</span> <span class="n">username</span>
        <span class="k">if</span> <span class="n">remote_addr</span> <span class="ow">is</span> <span class="bp">None</span> <span class="ow">and</span> <span class="n">has_request_context</span><span class="p">():</span>
            <span class="n">remote_addr</span> <span class="o">=</span> <span class="n">request</span><span class="o">.</span><span class="n">remote_addr</span>
        <span class="bp">self</span><span class="o">.</span><span class="n">remote_addr</span> <span class="o">=</span> <span class="n">remote_addr</span>
</pre></div>
</div>
<p>Alternatively you can also just test any of the context bound objects
(such as <a class="reference internal" href="#flask.request" title="flask.request"><tt class="xref py py-class docutils literal"><span class="pre">request</span></tt></a> or <a class="reference internal" href="#flask.g" title="flask.g"><tt class="xref py py-class docutils literal"><span class="pre">g</span></tt></a> for truthness):</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">class</span> <span class="nc">User</span><span class="p">(</span><span class="n">db</span><span class="o">.</span><span class="n">Model</span><span class="p">):</span>

    <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">username</span><span class="p">,</span> <span class="n">remote_addr</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
        <span class="bp">self</span><span class="o">.</span><span class="n">username</span> <span class="o">=</span> <span class="n">username</span>
        <span class="k">if</span> <span class="n">remote_addr</span> <span class="ow">is</span> <span class="bp">None</span> <span class="ow">and</span> <span class="n">request</span><span class="p">:</span>
            <span class="n">remote_addr</span> <span class="o">=</span> <span class="n">request</span><span class="o">.</span><span class="n">remote_addr</span>
        <span class="bp">self</span><span class="o">.</span><span class="n">remote_addr</span> <span class="o">=</span> <span class="n">remote_addr</span>
</pre></div>
</div>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
</dd></dl>

<dl class="function">
<dt id="flask.url_for">
<tt class="descclassname">flask.</tt><tt class="descname">url_for</tt><big>(</big><em>endpoint</em>, <em>**values</em><big>)</big><a class="headerlink" href="#flask.url_for" title="Permalink to this definition">¶</a></dt>
<dd><p>Generates a URL to the given endpoint with the method provided.</p>
<p>Variable arguments that are unknown to the target endpoint are appended
to the generated URL as query arguments.  If the value of a query argument
is <cite>None</cite>, the whole pair is skipped.  In case blueprints are active
you can shortcut references to the same blueprint by prefixing the
local endpoint with a dot (<tt class="docutils literal"><span class="pre">.</span></tt>).</p>
<p>This will reference the index function local to the current blueprint:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">url_for</span><span class="p">(</span><span class="s">&#39;.index&#39;</span><span class="p">)</span>
</pre></div>
</div>
<p>For more information, head over to the <a class="reference internal" href="quickstart.html#url-building"><em>Quickstart</em></a>.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>endpoint</strong> &#8211; the endpoint of the URL (name of the function)</li>
<li><strong>values</strong> &#8211; the variable arguments of the URL rule</li>
<li><strong>_external</strong> &#8211; if set to <cite>True</cite>, an absolute URL is generated.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="function">
<dt id="flask.abort">
<tt class="descclassname">flask.</tt><tt class="descname">abort</tt><big>(</big><em>code</em><big>)</big><a class="headerlink" href="#flask.abort" title="Permalink to this definition">¶</a></dt>
<dd><p>Raises an <a class="reference external" href="http://werkzeug.pocoo.org/docs/exceptions/#werkzeug.exceptions.HTTPException" title="(in Werkzeug v0.7)"><tt class="xref py py-exc docutils literal"><span class="pre">HTTPException</span></tt></a> for the given
status code.  For example to abort request handling with a page not
found exception, you would call <tt class="docutils literal"><span class="pre">abort(404)</span></tt>.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>code</strong> &#8211; the HTTP error code.</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="function">
<dt id="flask.redirect">
<tt class="descclassname">flask.</tt><tt class="descname">redirect</tt><big>(</big><em>location</em>, <em>code=302</em><big>)</big><a class="headerlink" href="#flask.redirect" title="Permalink to this definition">¶</a></dt>
<dd><p>Return a response object (a WSGI application) that, if called,
redirects the client to the target location.  Supported codes are 301,
302, 303, 305, and 307.  300 is not supported because it&#8217;s not a real
redirect and 304 because it&#8217;s the answer for a request with a request
with defined If-Modified-Since headers.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.6: </span>The location can now be a unicode string that is encoded using
the <tt class="xref py py-func docutils literal"><span class="pre">iri_to_uri()</span></tt> function.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>location</strong> &#8211; the location the response should redirect to.</li>
<li><strong>code</strong> &#8211; the redirect status code. defaults to 302.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="function">
<dt id="flask.make_response">
<tt class="descclassname">flask.</tt><tt class="descname">make_response</tt><big>(</big><em>*args</em><big>)</big><a class="headerlink" href="#flask.make_response" title="Permalink to this definition">¶</a></dt>
<dd><p>Sometimes it is necessary to set additional headers in a view.  Because
views do not have to return response objects but can return a value that
is converted into a response object by Flask itself, it becomes tricky to
add headers to it.  This function can be called instead of using a return
and you will get a response object which you can use to attach headers.</p>
<p>If view looked like this and you want to add a new header:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">def</span> <span class="nf">index</span><span class="p">():</span>
    <span class="k">return</span> <span class="n">render_template</span><span class="p">(</span><span class="s">&#39;index.html&#39;</span><span class="p">,</span> <span class="n">foo</span><span class="o">=</span><span class="mi">42</span><span class="p">)</span>
</pre></div>
</div>
<p>You can now do something like this:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">def</span> <span class="nf">index</span><span class="p">():</span>
    <span class="n">response</span> <span class="o">=</span> <span class="n">make_response</span><span class="p">(</span><span class="n">render_template</span><span class="p">(</span><span class="s">&#39;index.html&#39;</span><span class="p">,</span> <span class="n">foo</span><span class="o">=</span><span class="mi">42</span><span class="p">))</span>
    <span class="n">response</span><span class="o">.</span><span class="n">headers</span><span class="p">[</span><span class="s">&#39;X-Parachutes&#39;</span><span class="p">]</span> <span class="o">=</span> <span class="s">&#39;parachutes are cool&#39;</span>
    <span class="k">return</span> <span class="n">response</span>
</pre></div>
</div>
<p>This function accepts the very same arguments you can return from a
view function.  This for example creates a response with a 404 error
code:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">response</span> <span class="o">=</span> <span class="n">make_response</span><span class="p">(</span><span class="n">render_template</span><span class="p">(</span><span class="s">&#39;not_found.html&#39;</span><span class="p">),</span> <span class="mi">404</span><span class="p">)</span>
</pre></div>
</div>
<p>The other use case of this function is to force the return value of a
view function into a response which is helpful with view
decorators:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">response</span> <span class="o">=</span> <span class="n">make_response</span><span class="p">(</span><span class="n">view_function</span><span class="p">())</span>
<span class="n">response</span><span class="o">.</span><span class="n">headers</span><span class="p">[</span><span class="s">&#39;X-Parachutes&#39;</span><span class="p">]</span> <span class="o">=</span> <span class="s">&#39;parachutes are cool&#39;</span>
</pre></div>
</div>
<p>Internally this function does the following things:</p>
<ul class="simple">
<li>if no arguments are passed, it creates a new response argument</li>
<li>if one argument is passed, <a class="reference internal" href="#flask.Flask.make_response" title="flask.Flask.make_response"><tt class="xref py py-meth docutils literal"><span class="pre">flask.Flask.make_response()</span></tt></a>
is invoked with it.</li>
<li>if more than one argument is passed, the arguments are passed
to the <a class="reference internal" href="#flask.Flask.make_response" title="flask.Flask.make_response"><tt class="xref py py-meth docutils literal"><span class="pre">flask.Flask.make_response()</span></tt></a> function as tuple.</li>
</ul>
<p class="versionadded">
<span class="versionmodified">New in version 0.6.</span></p>
</dd></dl>

<dl class="function">
<dt id="flask.send_file">
<tt class="descclassname">flask.</tt><tt class="descname">send_file</tt><big>(</big><em>filename_or_fp</em>, <em>mimetype=None</em>, <em>as_attachment=False</em>, <em>attachment_filename=None</em>, <em>add_etags=True</em>, <em>cache_timeout=43200</em>, <em>conditional=False</em><big>)</big><a class="headerlink" href="#flask.send_file" title="Permalink to this definition">¶</a></dt>
<dd><p>Sends the contents of a file to the client.  This will use the
most efficient method available and configured.  By default it will
try to use the WSGI server&#8217;s file_wrapper support.  Alternatively
you can set the application&#8217;s <a class="reference internal" href="#flask.Flask.use_x_sendfile" title="flask.Flask.use_x_sendfile"><tt class="xref py py-attr docutils literal"><span class="pre">use_x_sendfile</span></tt></a> attribute
to <tt class="docutils literal"><span class="pre">True</span></tt> to directly emit an <cite>X-Sendfile</cite> header.  This however
requires support of the underlying webserver for <cite>X-Sendfile</cite>.</p>
<p>By default it will try to guess the mimetype for you, but you can
also explicitly provide one.  For extra security you probably want
to send certain files as attachment (HTML for instance).  The mimetype
guessing requires a <cite>filename</cite> or an <cite>attachment_filename</cite> to be
provided.</p>
<p>Please never pass filenames to this function from user sources without
checking them first.  Something like this is usually sufficient to
avoid security problems:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">if</span> <span class="s">&#39;..&#39;</span> <span class="ow">in</span> <span class="n">filename</span> <span class="ow">or</span> <span class="n">filename</span><span class="o">.</span><span class="n">startswith</span><span class="p">(</span><span class="s">&#39;/&#39;</span><span class="p">):</span>
    <span class="n">abort</span><span class="p">(</span><span class="mi">404</span><span class="p">)</span>
</pre></div>
</div>
<p class="versionadded">
<span class="versionmodified">New in version 0.2.</span></p>
<p class="versionadded">
<span class="versionmodified">New in version 0.5: </span>The <cite>add_etags</cite>, <cite>cache_timeout</cite> and <cite>conditional</cite> parameters were
added.  The default behaviour is now to attach etags.</p>
<p class="versionchanged">
<span class="versionmodified">Changed in version 0.7: </span>mimetype guessing and etag support for file objects was
deprecated because it was unreliable.  Pass a filename if you are
able to, otherwise attach an etag yourself.  This functionality
will be removed in Flask 1.0</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>filename_or_fp</strong> &#8211; the filename of the file to send.  This is
relative to the <tt class="xref py py-attr docutils literal"><span class="pre">root_path</span></tt> if a
relative path is specified.
Alternatively a file object might be provided
in which case <cite>X-Sendfile</cite> might not work and
fall back to the traditional method.  Make sure
that the file pointer is positioned at the start
of data to send before calling <a class="reference internal" href="#flask.send_file" title="flask.send_file"><tt class="xref py py-func docutils literal"><span class="pre">send_file()</span></tt></a>.</li>
<li><strong>mimetype</strong> &#8211; the mimetype of the file if provided, otherwise
auto detection happens.</li>
<li><strong>as_attachment</strong> &#8211; set to <cite>True</cite> if you want to send this file with
a <tt class="docutils literal"><span class="pre">Content-Disposition:</span> <span class="pre">attachment</span></tt> header.</li>
<li><strong>attachment_filename</strong> &#8211; the filename for the attachment if it
differs from the file&#8217;s filename.</li>
<li><strong>add_etags</strong> &#8211; set to <cite>False</cite> to disable attaching of etags.</li>
<li><strong>conditional</strong> &#8211; set to <cite>True</cite> to enable conditional responses.</li>
<li><strong>cache_timeout</strong> &#8211; the timeout in seconds for the headers.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="function">
<dt id="flask.send_from_directory">
<tt class="descclassname">flask.</tt><tt class="descname">send_from_directory</tt><big>(</big><em>directory</em>, <em>filename</em>, <em>**options</em><big>)</big><a class="headerlink" href="#flask.send_from_directory" title="Permalink to this definition">¶</a></dt>
<dd><p>Send a file from a given directory with <a class="reference internal" href="#flask.send_file" title="flask.send_file"><tt class="xref py py-func docutils literal"><span class="pre">send_file()</span></tt></a>.  This
is a secure way to quickly expose static files from an upload folder
or something similar.</p>
<p>Example usage:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="nd">@app.route</span><span class="p">(</span><span class="s">&#39;/uploads/&lt;path:filename&gt;&#39;</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">download_file</span><span class="p">(</span><span class="n">filename</span><span class="p">):</span>
    <span class="k">return</span> <span class="n">send_from_directory</span><span class="p">(</span><span class="n">app</span><span class="o">.</span><span class="n">config</span><span class="p">[</span><span class="s">&#39;UPLOAD_FOLDER&#39;</span><span class="p">],</span>
                               <span class="n">filename</span><span class="p">,</span> <span class="n">as_attachment</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span>
</pre></div>
</div>
<div class="admonition-sending-files-and-performance admonition ">
<p class="first admonition-title">Sending files and Performance</p>
<p class="last">It is strongly recommended to activate either <cite>X-Sendfile</cite> support in
your webserver or (if no authentication happens) to tell the webserver
to serve files for the given path on its own without calling into the
web application for improved performance.</p>
</div>
<p class="versionadded">
<span class="versionmodified">New in version 0.5.</span></p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>directory</strong> &#8211; the directory where all the files are stored.</li>
<li><strong>filename</strong> &#8211; the filename relative to that directory to
download.</li>
<li><strong>options</strong> &#8211; optional keyword arguments that are directly
forwarded to <a class="reference internal" href="#flask.send_file" title="flask.send_file"><tt class="xref py py-func docutils literal"><span class="pre">send_file()</span></tt></a>.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="function">
<dt id="flask.safe_join">
<tt class="descclassname">flask.</tt><tt class="descname">safe_join</tt><big>(</big><em>directory</em>, <em>filename</em><big>)</big><a class="headerlink" href="#flask.safe_join" title="Permalink to this definition">¶</a></dt>
<dd><p>Safely join <cite>directory</cite> and <cite>filename</cite>.</p>
<p>Example usage:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="nd">@app.route</span><span class="p">(</span><span class="s">&#39;/wiki/&lt;path:filename&gt;&#39;</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">wiki_page</span><span class="p">(</span><span class="n">filename</span><span class="p">):</span>
    <span class="n">filename</span> <span class="o">=</span> <span class="n">safe_join</span><span class="p">(</span><span class="n">app</span><span class="o">.</span><span class="n">config</span><span class="p">[</span><span class="s">&#39;WIKI_FOLDER&#39;</span><span class="p">],</span> <span class="n">filename</span><span class="p">)</span>
    <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span> <span class="s">&#39;rb&#39;</span><span class="p">)</span> <span class="k">as</span> <span class="n">fd</span><span class="p">:</span>
        <span class="n">content</span> <span class="o">=</span> <span class="n">fd</span><span class="o">.</span><span class="n">read</span><span class="p">()</span> <span class="c"># Read and process the file content...</span>
</pre></div>
</div>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>directory</strong> &#8211; the base directory.</li>
<li><strong>filename</strong> &#8211; the untrusted filename relative to that directory.</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Raises :</th><td class="field-body"><p class="first last"><tt class="xref py py-class docutils literal"><span class="pre">NotFound</span></tt> if the resulting path
would fall out of <cite>directory</cite>.</p>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="function">
<dt id="flask.escape">
<tt class="descclassname">flask.</tt><tt class="descname">escape</tt><big>(</big><em>s</em><big>)</big> &rarr; markup<a class="headerlink" href="#flask.escape" title="Permalink to this definition">¶</a></dt>
<dd><p>Convert the characters &amp;, &lt;, &gt;, &#8216;, and &#8221; in string s to HTML-safe
sequences.  Use this if you need to display text that might contain
such characters in HTML.  Marks return value as markup string.</p>
</dd></dl>

<dl class="class">
<dt id="flask.Markup">
<em class="property">class </em><tt class="descclassname">flask.</tt><tt class="descname">Markup</tt><a class="headerlink" href="#flask.Markup" title="Permalink to this definition">¶</a></dt>
<dd><p>Marks a string as being safe for inclusion in HTML/XML output without
needing to be escaped.  This implements the <cite>__html__</cite> interface a couple
of frameworks and web applications use.  <a class="reference internal" href="#flask.Markup" title="flask.Markup"><tt class="xref py py-class docutils literal"><span class="pre">Markup</span></tt></a> is a direct
subclass of <cite>unicode</cite> and provides all the methods of <cite>unicode</cite> just that
it escapes arguments passed and always returns <cite>Markup</cite>.</p>
<p>The <cite>escape</cite> function returns markup objects so that double escaping can&#8217;t
happen.</p>
<p>The constructor of the <a class="reference internal" href="#flask.Markup" title="flask.Markup"><tt class="xref py py-class docutils literal"><span class="pre">Markup</span></tt></a> class can be used for three
different things:  When passed an unicode object it&#8217;s assumed to be safe,
when passed an object with an HTML representation (has an <cite>__html__</cite>
method) that representation is used, otherwise the object passed is
converted into a unicode string and then assumed to be safe:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">Markup</span><span class="p">(</span><span class="s">&quot;Hello &lt;em&gt;World&lt;/em&gt;!&quot;</span><span class="p">)</span>
<span class="go">Markup(u&#39;Hello &lt;em&gt;World&lt;/em&gt;!&#39;)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="k">class</span> <span class="nc">Foo</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="gp">... </span> <span class="k">def</span> <span class="nf">__html__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="gp">... </span>  <span class="k">return</span> <span class="s">&#39;&lt;a href=&quot;#&quot;&gt;foo&lt;/a&gt;&#39;</span>
<span class="gp">... </span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">Markup</span><span class="p">(</span><span class="n">Foo</span><span class="p">())</span>
<span class="go">Markup(u&#39;&lt;a href=&quot;#&quot;&gt;foo&lt;/a&gt;&#39;)</span>
</pre></div>
</div>
<p>If you want object passed being always treated as unsafe you can use the
<a class="reference internal" href="#flask.escape" title="flask.escape"><tt class="xref py py-meth docutils literal"><span class="pre">escape()</span></tt></a> classmethod to create a <a class="reference internal" href="#flask.Markup" title="flask.Markup"><tt class="xref py py-class docutils literal"><span class="pre">Markup</span></tt></a> object:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">Markup</span><span class="o">.</span><span class="n">escape</span><span class="p">(</span><span class="s">&quot;Hello &lt;em&gt;World&lt;/em&gt;!&quot;</span><span class="p">)</span>
<span class="go">Markup(u&#39;Hello &amp;lt;em&amp;gt;World&amp;lt;/em&amp;gt;!&#39;)</span>
</pre></div>
</div>
<p>Operations on a markup string are markup aware which means that all
arguments are passed through the <a class="reference internal" href="#flask.escape" title="flask.escape"><tt class="xref py py-func docutils literal"><span class="pre">escape()</span></tt></a> function:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">em</span> <span class="o">=</span> <span class="n">Markup</span><span class="p">(</span><span class="s">&quot;&lt;em&gt;</span><span class="si">%s</span><span class="s">&lt;/em&gt;&quot;</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">em</span> <span class="o">%</span> <span class="s">&quot;foo &amp; bar&quot;</span>
<span class="go">Markup(u&#39;&lt;em&gt;foo &amp;amp; bar&lt;/em&gt;&#39;)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">strong</span> <span class="o">=</span> <span class="n">Markup</span><span class="p">(</span><span class="s">&quot;&lt;strong&gt;</span><span class="si">%(text)s</span><span class="s">&lt;/strong&gt;&quot;</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">strong</span> <span class="o">%</span> <span class="p">{</span><span class="s">&#39;text&#39;</span><span class="p">:</span> <span class="s">&#39;&lt;blink&gt;hacker here&lt;/blink&gt;&#39;</span><span class="p">}</span>
<span class="go">Markup(u&#39;&lt;strong&gt;&amp;lt;blink&amp;gt;hacker here&amp;lt;/blink&amp;gt;&lt;/strong&gt;&#39;)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">Markup</span><span class="p">(</span><span class="s">&quot;&lt;em&gt;Hello&lt;/em&gt; &quot;</span><span class="p">)</span> <span class="o">+</span> <span class="s">&quot;&lt;foo&gt;&quot;</span>
<span class="go">Markup(u&#39;&lt;em&gt;Hello&lt;/em&gt; &amp;lt;foo&amp;gt;&#39;)</span>
</pre></div>
</div>
<dl class="classmethod">
<dt id="flask.Markup.escape">
<em class="property">classmethod </em><tt class="descname">escape</tt><big>(</big><em>s</em><big>)</big><a class="headerlink" href="#flask.Markup.escape" title="Permalink to this definition">¶</a></dt>
<dd><p>Escape the string.  Works like <a class="reference internal" href="#flask.escape" title="flask.escape"><tt class="xref py py-func docutils literal"><span class="pre">escape()</span></tt></a> with the difference
that for subclasses of <a class="reference internal" href="#flask.Markup" title="flask.Markup"><tt class="xref py py-class docutils literal"><span class="pre">Markup</span></tt></a> this function would return the
correct subclass.</p>
</dd></dl>

<dl class="method">
<dt id="flask.Markup.unescape">
<tt class="descname">unescape</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.Markup.unescape" title="Permalink to this definition">¶</a></dt>
<dd><p>Unescape markup again into an unicode string.  This also resolves
known HTML4 and XHTML entities:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">Markup</span><span class="p">(</span><span class="s">&quot;Main &amp;raquo; &lt;em&gt;About&lt;/em&gt;&quot;</span><span class="p">)</span><span class="o">.</span><span class="n">unescape</span><span class="p">()</span>
<span class="go">u&#39;Main \xbb &lt;em&gt;About&lt;/em&gt;&#39;</span>
</pre></div>
</div>
</dd></dl>

<dl class="method">
<dt id="flask.Markup.striptags">
<tt class="descname">striptags</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.Markup.striptags" title="Permalink to this definition">¶</a></dt>
<dd><p>Unescape markup into an unicode string and strip all tags.  This
also resolves known HTML4 and XHTML entities.  Whitespace is
normalized to one:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">Markup</span><span class="p">(</span><span class="s">&quot;Main &amp;raquo;  &lt;em&gt;About&lt;/em&gt;&quot;</span><span class="p">)</span><span class="o">.</span><span class="n">striptags</span><span class="p">()</span>
<span class="go">u&#39;Main \xbb About&#39;</span>
</pre></div>
</div>
</dd></dl>

</dd></dl>

</div>
<div class="section" id="message-flashing">
<h2>Message Flashing<a class="headerlink" href="#message-flashing" title="Permalink to this headline">¶</a></h2>
<dl class="function">
<dt id="flask.flash">
<tt class="descclassname">flask.</tt><tt class="descname">flash</tt><big>(</big><em>message</em>, <em>category='message'</em><big>)</big><a class="headerlink" href="#flask.flash" title="Permalink to this definition">¶</a></dt>
<dd><p>Flashes a message to the next request.  In order to remove the
flashed message from the session and to display it to the user,
the template has to call <a class="reference internal" href="#flask.get_flashed_messages" title="flask.get_flashed_messages"><tt class="xref py py-func docutils literal"><span class="pre">get_flashed_messages()</span></tt></a>.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>message</strong> &#8211; the message to be flashed.</li>
<li><strong>category</strong> &#8211; the category for the message.  The following values
are recommended: <tt class="docutils literal"><span class="pre">'message'</span></tt> for any kind of message,
<tt class="docutils literal"><span class="pre">'error'</span></tt> for errors, <tt class="docutils literal"><span class="pre">'info'</span></tt> for information
messages and <tt class="docutils literal"><span class="pre">'warning'</span></tt> for warnings.  However any
kind of string can be used as category.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="function">
<dt id="flask.get_flashed_messages">
<tt class="descclassname">flask.</tt><tt class="descname">get_flashed_messages</tt><big>(</big><em>with_categories=False</em><big>)</big><a class="headerlink" href="#flask.get_flashed_messages" title="Permalink to this definition">¶</a></dt>
<dd><p>Pulls all flashed messages from the session and returns them.
Further calls in the same request to the function will return
the same messages.  By default just the messages are returned,
but when <cite>with_categories</cite> is set to <cite>True</cite>, the return value will
be a list of tuples in the form <tt class="docutils literal"><span class="pre">(category,</span> <span class="pre">message)</span></tt> instead.</p>
<p>Example usage:</p>
<div class="highlight-html+jinja"><div class="highlight"><pre><span class="cp">{%</span> <span class="k">for</span> <span class="nv">category</span><span class="o">,</span> <span class="nv">msg</span> <span class="k">in</span> <span class="nv">get_flashed_messages</span><span class="o">(</span><span class="nv">with_categories</span><span class="o">=</span><span class="kp">true</span><span class="o">)</span> <span class="cp">%}</span>
  <span class="nt">&lt;p</span> <span class="na">class=</span><span class="s">flash-</span><span class="cp">{{</span> <span class="nv">category</span> <span class="cp">}}</span><span class="nt">&gt;</span><span class="cp">{{</span> <span class="nv">msg</span> <span class="cp">}}</span>
<span class="cp">{%</span> <span class="k">endfor</span> <span class="cp">%}</span>
</pre></div>
</div>
<p class="versionchanged">
<span class="versionmodified">Changed in version 0.3: </span><cite>with_categories</cite> parameter added.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>with_categories</strong> &#8211; set to <cite>True</cite> to also receive categories.</td>
</tr>
</tbody>
</table>
</dd></dl>

</div>
<div class="section" id="returning-json">
<h2>Returning JSON<a class="headerlink" href="#returning-json" title="Permalink to this headline">¶</a></h2>
<dl class="function">
<dt id="flask.jsonify">
<tt class="descclassname">flask.</tt><tt class="descname">jsonify</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#flask.jsonify" title="Permalink to this definition">¶</a></dt>
<dd><p>Creates a <a class="reference internal" href="#flask.Response" title="flask.Response"><tt class="xref py py-class docutils literal"><span class="pre">Response</span></tt></a> with the JSON representation of
the given arguments with an <cite>application/json</cite> mimetype.  The arguments
to this function are the same as to the <a class="reference external" href="http://docs.python.org/dev/library/stdtypes.html#dict" title="(in Python v3.3)"><tt class="xref py py-class docutils literal"><span class="pre">dict</span></tt></a> constructor.</p>
<p>Example usage:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="nd">@app.route</span><span class="p">(</span><span class="s">&#39;/_get_current_user&#39;</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">get_current_user</span><span class="p">():</span>
    <span class="k">return</span> <span class="n">jsonify</span><span class="p">(</span><span class="n">username</span><span class="o">=</span><span class="n">g</span><span class="o">.</span><span class="n">user</span><span class="o">.</span><span class="n">username</span><span class="p">,</span>
                   <span class="n">email</span><span class="o">=</span><span class="n">g</span><span class="o">.</span><span class="n">user</span><span class="o">.</span><span class="n">email</span><span class="p">,</span>
                   <span class="nb">id</span><span class="o">=</span><span class="n">g</span><span class="o">.</span><span class="n">user</span><span class="o">.</span><span class="n">id</span><span class="p">)</span>
</pre></div>
</div>
<p>This will send a JSON response like this to the browser:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="p">{</span>
    <span class="s">&quot;username&quot;</span><span class="p">:</span> <span class="s">&quot;admin&quot;</span><span class="p">,</span>
    <span class="s">&quot;email&quot;</span><span class="p">:</span> <span class="s">&quot;admin@localhost&quot;</span><span class="p">,</span>
    <span class="s">&quot;id&quot;</span><span class="p">:</span> <span class="mi">42</span>
<span class="p">}</span>
</pre></div>
</div>
<p>This requires Python 2.6 or an installed version of simplejson.  For
security reasons only objects are supported toplevel.  For more
information about this, have a look at <a class="reference internal" href="security.html#json-security"><em>JSON Security</em></a>.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.2.</span></p>
</dd></dl>

<dl class="data">
<dt id="flask.json">
<tt class="descclassname">flask.</tt><tt class="descname">json</tt><a class="headerlink" href="#flask.json" title="Permalink to this definition">¶</a></dt>
<dd><p>If JSON support is picked up, this will be the module that Flask is
using to parse and serialize JSON.  So instead of doing this yourself:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">try</span><span class="p">:</span>
    <span class="kn">import</span> <span class="nn">simplejson</span> <span class="kn">as</span> <span class="nn">json</span>
<span class="k">except</span> <span class="ne">ImportError</span><span class="p">:</span>
    <span class="kn">import</span> <span class="nn">json</span>
</pre></div>
</div>
<p>You can instead just do this:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">flask</span> <span class="kn">import</span> <span class="n">json</span>
</pre></div>
</div>
<p>For usage examples, read the <a class="reference external" href="http://docs.python.org/dev/library/json.html#json" title="(in Python v3.3)"><tt class="xref py py-mod docutils literal"><span class="pre">json</span></tt></a> documentation.</p>
<p>The <a class="reference external" href="http://docs.python.org/dev/library/json.html#json.dumps" title="(in Python v3.3)"><tt class="xref py py-func docutils literal"><span class="pre">dumps()</span></tt></a> function of this json module is also available
as filter called <tt class="docutils literal"><span class="pre">|tojson</span></tt> in Jinja2.  Note that inside <cite>script</cite>
tags no escaping must take place, so make sure to disable escaping
with <tt class="docutils literal"><span class="pre">|safe</span></tt> if you intend to use it inside <cite>script</cite> tags:</p>
<div class="highlight-html+jinja"><div class="highlight"><pre><span class="nt">&lt;script </span><span class="na">type=</span><span class="s">text/javascript</span><span class="nt">&gt;</span>
    <span class="nx">doSomethingWith</span><span class="p">(</span><span class="cp">{{</span> <span class="nv">user.username</span><span class="o">|</span><span class="nf">tojson</span><span class="o">|</span><span class="nf">safe</span> <span class="cp">}}</span><span class="p">);</span>
<span class="nt">&lt;/script&gt;</span>
</pre></div>
</div>
<p>Note that the <tt class="docutils literal"><span class="pre">|tojson</span></tt> filter escapes forward slashes properly.</p>
</dd></dl>

</div>
<div class="section" id="template-rendering">
<h2>Template Rendering<a class="headerlink" href="#template-rendering" title="Permalink to this headline">¶</a></h2>
<dl class="function">
<dt id="flask.render_template">
<tt class="descclassname">flask.</tt><tt class="descname">render_template</tt><big>(</big><em>template_name</em>, <em>**context</em><big>)</big><a class="headerlink" href="#flask.render_template" title="Permalink to this definition">¶</a></dt>
<dd><p>Renders a template from the template folder with the given
context.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>template_name</strong> &#8211; the name of the template to be rendered</li>
<li><strong>context</strong> &#8211; the variables that should be available in the
context of the template.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="function">
<dt id="flask.render_template_string">
<tt class="descclassname">flask.</tt><tt class="descname">render_template_string</tt><big>(</big><em>source</em>, <em>**context</em><big>)</big><a class="headerlink" href="#flask.render_template_string" title="Permalink to this definition">¶</a></dt>
<dd><p>Renders a template from the given template source string
with the given context.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>template_name</strong> &#8211; the sourcecode of the template to be
rendered</li>
<li><strong>context</strong> &#8211; the variables that should be available in the
context of the template.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="function">
<dt id="flask.get_template_attribute">
<tt class="descclassname">flask.</tt><tt class="descname">get_template_attribute</tt><big>(</big><em>template_name</em>, <em>attribute</em><big>)</big><a class="headerlink" href="#flask.get_template_attribute" title="Permalink to this definition">¶</a></dt>
<dd><p>Loads a macro (or variable) a template exports.  This can be used to
invoke a macro from within Python code.  If you for example have a
template named <cite>_cider.html</cite> with the following contents:</p>
<div class="highlight-html+jinja"><div class="highlight"><pre><span class="cp">{%</span> <span class="k">macro</span> <span class="nv">hello</span><span class="o">(</span><span class="nv">name</span><span class="o">)</span> <span class="cp">%}</span>Hello <span class="cp">{{</span> <span class="nv">name</span> <span class="cp">}}</span>!<span class="cp">{%</span> <span class="k">endmacro</span> <span class="cp">%}</span>
</pre></div>
</div>
<p>You can access this from Python code like this:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">hello</span> <span class="o">=</span> <span class="n">get_template_attribute</span><span class="p">(</span><span class="s">&#39;_cider.html&#39;</span><span class="p">,</span> <span class="s">&#39;hello&#39;</span><span class="p">)</span>
<span class="k">return</span> <span class="n">hello</span><span class="p">(</span><span class="s">&#39;World&#39;</span><span class="p">)</span>
</pre></div>
</div>
<p class="versionadded">
<span class="versionmodified">New in version 0.2.</span></p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>template_name</strong> &#8211; the name of the template</li>
<li><strong>attribute</strong> &#8211; the name of the variable of macro to acccess</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

</div>
<div class="section" id="configuration">
<h2>Configuration<a class="headerlink" href="#configuration" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="flask.Config">
<em class="property">class </em><tt class="descclassname">flask.</tt><tt class="descname">Config</tt><big>(</big><em>root_path</em>, <em>defaults=None</em><big>)</big><a class="headerlink" href="#flask.Config" title="Permalink to this definition">¶</a></dt>
<dd><p>Works exactly like a dict but provides ways to fill it from files
or special dictionaries.  There are two common patterns to populate the
config.</p>
<p>Either you can fill the config from a config file:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">app</span><span class="o">.</span><span class="n">config</span><span class="o">.</span><span class="n">from_pyfile</span><span class="p">(</span><span class="s">&#39;yourconfig.cfg&#39;</span><span class="p">)</span>
</pre></div>
</div>
<p>Or alternatively you can define the configuration options in the
module that calls <a class="reference internal" href="#flask.Config.from_object" title="flask.Config.from_object"><tt class="xref py py-meth docutils literal"><span class="pre">from_object()</span></tt></a> or provide an import path to
a module that should be loaded.  It is also possible to tell it to
use the same module and with that provide the configuration values
just before the call:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">DEBUG</span> <span class="o">=</span> <span class="bp">True</span>
<span class="n">SECRET_KEY</span> <span class="o">=</span> <span class="s">&#39;development key&#39;</span>
<span class="n">app</span><span class="o">.</span><span class="n">config</span><span class="o">.</span><span class="n">from_object</span><span class="p">(</span><span class="n">__name__</span><span class="p">)</span>
</pre></div>
</div>
<p>In both cases (loading from any Python file or loading from modules),
only uppercase keys are added to the config.  This makes it possible to use
lowercase values in the config file for temporary values that are not added
to the config or to define the config keys in the same file that implements
the application.</p>
<p>Probably the most interesting way to load configurations is from an
environment variable pointing to a file:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">app</span><span class="o">.</span><span class="n">config</span><span class="o">.</span><span class="n">from_envvar</span><span class="p">(</span><span class="s">&#39;YOURAPPLICATION_SETTINGS&#39;</span><span class="p">)</span>
</pre></div>
</div>
<p>In this case before launching the application you have to set this
environment variable to the file you want to use.  On Linux and OS X
use the export statement:</p>
<div class="highlight-python"><pre>export YOURAPPLICATION_SETTINGS='/path/to/config/file'</pre>
</div>
<p>On windows use <cite>set</cite> instead.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>root_path</strong> &#8211; path to which files are read relative from.  When the
config object is created by the application, this is
the application&#8217;s <tt class="xref py py-attr docutils literal"><span class="pre">root_path</span></tt>.</li>
<li><strong>defaults</strong> &#8211; an optional dictionary of default values</li>
</ul>
</td>
</tr>
</tbody>
</table>
<dl class="method">
<dt id="flask.Config.from_envvar">
<tt class="descname">from_envvar</tt><big>(</big><em>variable_name</em>, <em>silent=False</em><big>)</big><a class="headerlink" href="#flask.Config.from_envvar" title="Permalink to this definition">¶</a></dt>
<dd><p>Loads a configuration from an environment variable pointing to
a configuration file.  This is basically just a shortcut with nicer
error messages for this line of code:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">app</span><span class="o">.</span><span class="n">config</span><span class="o">.</span><span class="n">from_pyfile</span><span class="p">(</span><span class="n">os</span><span class="o">.</span><span class="n">environ</span><span class="p">[</span><span class="s">&#39;YOURAPPLICATION_SETTINGS&#39;</span><span class="p">])</span>
</pre></div>
</div>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>variable_name</strong> &#8211; name of the environment variable</li>
<li><strong>silent</strong> &#8211; set to <cite>True</cite> if you want silent failure for missing
files.</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first last">bool. <cite>True</cite> if able to load config, <cite>False</cite> otherwise.</p>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="method">
<dt id="flask.Config.from_object">
<tt class="descname">from_object</tt><big>(</big><em>obj</em><big>)</big><a class="headerlink" href="#flask.Config.from_object" title="Permalink to this definition">¶</a></dt>
<dd><p>Updates the values from the given object.  An object can be of one
of the following two types:</p>
<ul class="simple">
<li>a string: in this case the object with that name will be imported</li>
<li>an actual object reference: that object is used directly</li>
</ul>
<p>Objects are usually either modules or classes.</p>
<p>Just the uppercase variables in that object are stored in the config.
Example usage:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">app</span><span class="o">.</span><span class="n">config</span><span class="o">.</span><span class="n">from_object</span><span class="p">(</span><span class="s">&#39;yourapplication.default_config&#39;</span><span class="p">)</span>
<span class="kn">from</span> <span class="nn">yourapplication</span> <span class="kn">import</span> <span class="n">default_config</span>
<span class="n">app</span><span class="o">.</span><span class="n">config</span><span class="o">.</span><span class="n">from_object</span><span class="p">(</span><span class="n">default_config</span><span class="p">)</span>
</pre></div>
</div>
<p>You should not use this function to load the actual configuration but
rather configuration defaults.  The actual config should be loaded
with <a class="reference internal" href="#flask.Config.from_pyfile" title="flask.Config.from_pyfile"><tt class="xref py py-meth docutils literal"><span class="pre">from_pyfile()</span></tt></a> and ideally from a location not within the
package because the package might be installed system wide.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>obj</strong> &#8211; an import name or object</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="method">
<dt id="flask.Config.from_pyfile">
<tt class="descname">from_pyfile</tt><big>(</big><em>filename</em>, <em>silent=False</em><big>)</big><a class="headerlink" href="#flask.Config.from_pyfile" title="Permalink to this definition">¶</a></dt>
<dd><p>Updates the values in the config from a Python file.  This function
behaves as if the file was imported as module with the
<a class="reference internal" href="#flask.Config.from_object" title="flask.Config.from_object"><tt class="xref py py-meth docutils literal"><span class="pre">from_object()</span></tt></a> function.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>filename</strong> &#8211; the filename of the config.  This can either be an
absolute filename or a filename relative to the
root path.</li>
<li><strong>silent</strong> &#8211; set to <cite>True</cite> if you want silent failure for missing
files.</li>
</ul>
</td>
</tr>
</tbody>
</table>
<p class="versionadded">
<span class="versionmodified">New in version 0.7: </span><cite>silent</cite> parameter.</p>
</dd></dl>

</dd></dl>

</div>
<div class="section" id="extensions">
<h2>Extensions<a class="headerlink" href="#extensions" title="Permalink to this headline">¶</a></h2>
<dl class="data">
<dt id="flask.flask.ext">
<tt class="descclassname">flask.</tt><tt class="descname">ext</tt><a class="headerlink" href="#flask.flask.ext" title="Permalink to this definition">¶</a></dt>
<dd><p>This module acts as redirect import module to Flask extensions.  It was
added in 0.8 as the canonical way to import Flask extensions and makes
it possible for us to have more flexibility in how we distribute
extensions.</p>
<p>If you want to use an extension named “Flask-Foo” you would import it
from <a class="reference internal" href="#flask.flask.ext" title="flask.flask.ext"><tt class="xref py py-data docutils literal"><span class="pre">ext</span></tt></a> as follows:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">flask.ext</span> <span class="kn">import</span> <span class="n">foo</span>
</pre></div>
</div>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
</dd></dl>

</div>
<div class="section" id="useful-internals">
<h2>Useful Internals<a class="headerlink" href="#useful-internals" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="flask.ctx.RequestContext">
<em class="property">class </em><tt class="descclassname">flask.ctx.</tt><tt class="descname">RequestContext</tt><big>(</big><em>app</em>, <em>environ</em><big>)</big><a class="headerlink" href="#flask.ctx.RequestContext" title="Permalink to this definition">¶</a></dt>
<dd><p>The request context contains all request relevant information.  It is
created at the beginning of the request and pushed to the
<cite>_request_ctx_stack</cite> and removed at the end of it.  It will create the
URL adapter and request object for the WSGI environment provided.</p>
<p>Do not attempt to use this class directly, instead use
<a class="reference internal" href="#flask.Flask.test_request_context" title="flask.Flask.test_request_context"><tt class="xref py py-meth docutils literal"><span class="pre">test_request_context()</span></tt></a> and
<a class="reference internal" href="#flask.Flask.request_context" title="flask.Flask.request_context"><tt class="xref py py-meth docutils literal"><span class="pre">request_context()</span></tt></a> to create this object.</p>
<p>When the request context is popped, it will evaluate all the
functions registered on the application for teardown execution
(<a class="reference internal" href="#flask.Flask.teardown_request" title="flask.Flask.teardown_request"><tt class="xref py py-meth docutils literal"><span class="pre">teardown_request()</span></tt></a>).</p>
<p>The request context is automatically popped at the end of the request
for you.  In debug mode the request context is kept around if
exceptions happen so that interactive debuggers have a chance to
introspect the data.  With 0.4 this can also be forced for requests
that did not fail and outside of <cite>DEBUG</cite> mode.  By setting
<tt class="docutils literal"><span class="pre">'flask._preserve_context'</span></tt> to <cite>True</cite> on the WSGI environment the
context will not pop itself at the end of the request.  This is used by
the <a class="reference internal" href="#flask.Flask.test_client" title="flask.Flask.test_client"><tt class="xref py py-meth docutils literal"><span class="pre">test_client()</span></tt></a> for example to implement the
deferred cleanup functionality.</p>
<p>You might find this helpful for unittests where you need the
information from the context local around for a little longer.  Make
sure to properly <tt class="xref py py-meth docutils literal"><span class="pre">pop()</span></tt> the stack yourself in
that situation, otherwise your unittests will leak memory.</p>
<dl class="method">
<dt id="flask.ctx.RequestContext.match_request">
<tt class="descname">match_request</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.ctx.RequestContext.match_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Can be overridden by a subclass to hook into the matching
of the request.</p>
</dd></dl>

<dl class="method">
<dt id="flask.ctx.RequestContext.pop">
<tt class="descname">pop</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.ctx.RequestContext.pop" title="Permalink to this definition">¶</a></dt>
<dd><p>Pops the request context and unbinds it by doing that.  This will
also trigger the execution of functions registered by the
<a class="reference internal" href="#flask.Flask.teardown_request" title="flask.Flask.teardown_request"><tt class="xref py py-meth docutils literal"><span class="pre">teardown_request()</span></tt></a> decorator.</p>
</dd></dl>

<dl class="method">
<dt id="flask.ctx.RequestContext.push">
<tt class="descname">push</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.ctx.RequestContext.push" title="Permalink to this definition">¶</a></dt>
<dd><p>Binds the request context to the current context.</p>
</dd></dl>

</dd></dl>

<dl class="data">
<dt id="flask._request_ctx_stack">
<tt class="descclassname">flask.</tt><tt class="descname">_request_ctx_stack</tt><a class="headerlink" href="#flask._request_ctx_stack" title="Permalink to this definition">¶</a></dt>
<dd><p>The internal <a class="reference external" href="http://werkzeug.pocoo.org/docs/local/#werkzeug.local.LocalStack" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">LocalStack</span></tt></a> that is used to implement
all the context local objects used in Flask.  This is a documented
instance and can be used by extensions and application code but the
use is discouraged in general.</p>
<p>The following attributes are always present on each layer of the
stack:</p>
<dl class="docutils">
<dt><cite>app</cite></dt>
<dd>the active Flask application.</dd>
<dt><cite>url_adapter</cite></dt>
<dd>the URL adapter that was used to match the request.</dd>
<dt><cite>request</cite></dt>
<dd>the current request object.</dd>
<dt><cite>session</cite></dt>
<dd>the active session object.</dd>
<dt><cite>g</cite></dt>
<dd>an object with all the attributes of the <a class="reference internal" href="#flask.g" title="flask.g"><tt class="xref py py-data docutils literal"><span class="pre">flask.g</span></tt></a> object.</dd>
<dt><cite>flashes</cite></dt>
<dd>an internal cache for the flashed messages.</dd>
</dl>
<p>Example usage:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">flask</span> <span class="kn">import</span> <span class="n">_request_ctx_stack</span>

<span class="k">def</span> <span class="nf">get_session</span><span class="p">():</span>
    <span class="n">ctx</span> <span class="o">=</span> <span class="n">_request_ctx_stack</span><span class="o">.</span><span class="n">top</span>
    <span class="k">if</span> <span class="n">ctx</span> <span class="ow">is</span> <span class="ow">not</span> <span class="bp">None</span><span class="p">:</span>
        <span class="k">return</span> <span class="n">ctx</span><span class="o">.</span><span class="n">session</span>
</pre></div>
</div>
</dd></dl>

<dl class="class">
<dt id="flask.blueprints.BlueprintSetupState">
<em class="property">class </em><tt class="descclassname">flask.blueprints.</tt><tt class="descname">BlueprintSetupState</tt><big>(</big><em>blueprint</em>, <em>app</em>, <em>options</em>, <em>first_registration</em><big>)</big><a class="headerlink" href="#flask.blueprints.BlueprintSetupState" title="Permalink to this definition">¶</a></dt>
<dd><p>Temporary holder object for registering a blueprint with the
application.  An instance of this class is created by the
<a class="reference internal" href="#flask.Blueprint.make_setup_state" title="flask.Blueprint.make_setup_state"><tt class="xref py py-meth docutils literal"><span class="pre">make_setup_state()</span></tt></a> method and later passed
to all register callback functions.</p>
<dl class="method">
<dt id="flask.blueprints.BlueprintSetupState.add_url_rule">
<tt class="descname">add_url_rule</tt><big>(</big><em>rule</em>, <em>endpoint=None</em>, <em>view_func=None</em>, <em>**options</em><big>)</big><a class="headerlink" href="#flask.blueprints.BlueprintSetupState.add_url_rule" title="Permalink to this definition">¶</a></dt>
<dd><p>A helper method to register a rule (and optionally a view function)
to the application.  The endpoint is automatically prefixed with the
blueprint&#8217;s name.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.blueprints.BlueprintSetupState.app">
<tt class="descname">app</tt><em class="property"> = None</em><a class="headerlink" href="#flask.blueprints.BlueprintSetupState.app" title="Permalink to this definition">¶</a></dt>
<dd><p>a reference to the current application</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.blueprints.BlueprintSetupState.blueprint">
<tt class="descname">blueprint</tt><em class="property"> = None</em><a class="headerlink" href="#flask.blueprints.BlueprintSetupState.blueprint" title="Permalink to this definition">¶</a></dt>
<dd><p>a reference to the blurprint that created this setup state.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.blueprints.BlueprintSetupState.first_registration">
<tt class="descname">first_registration</tt><em class="property"> = None</em><a class="headerlink" href="#flask.blueprints.BlueprintSetupState.first_registration" title="Permalink to this definition">¶</a></dt>
<dd><p>as blueprints can be registered multiple times with the
application and not everything wants to be registered
multiple times on it, this attribute can be used to figure
out if the blueprint was registered in the past already.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.blueprints.BlueprintSetupState.options">
<tt class="descname">options</tt><em class="property"> = None</em><a class="headerlink" href="#flask.blueprints.BlueprintSetupState.options" title="Permalink to this definition">¶</a></dt>
<dd><p>a dictionary with all options that were passed to the
<a class="reference internal" href="#flask.Flask.register_blueprint" title="flask.Flask.register_blueprint"><tt class="xref py py-meth docutils literal"><span class="pre">register_blueprint()</span></tt></a> method.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.blueprints.BlueprintSetupState.subdomain">
<tt class="descname">subdomain</tt><em class="property"> = None</em><a class="headerlink" href="#flask.blueprints.BlueprintSetupState.subdomain" title="Permalink to this definition">¶</a></dt>
<dd><p>The subdomain that the blueprint should be active for, <cite>None</cite>
otherwise.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.blueprints.BlueprintSetupState.url_defaults">
<tt class="descname">url_defaults</tt><em class="property"> = None</em><a class="headerlink" href="#flask.blueprints.BlueprintSetupState.url_defaults" title="Permalink to this definition">¶</a></dt>
<dd><p>A dictionary with URL defaults that is added to each and every
URL that was defined with the blueprint.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.blueprints.BlueprintSetupState.url_prefix">
<tt class="descname">url_prefix</tt><em class="property"> = None</em><a class="headerlink" href="#flask.blueprints.BlueprintSetupState.url_prefix" title="Permalink to this definition">¶</a></dt>
<dd><p>The prefix that should be used for all URLs defined on the
blueprint.</p>
</dd></dl>

</dd></dl>

</div>
<div class="section" id="signals">
<h2>Signals<a class="headerlink" href="#signals" title="Permalink to this headline">¶</a></h2>
<p class="versionadded">
<span class="versionmodified">New in version 0.6.</span></p>
<dl class="data">
<dt id="flask.signals_available">
<tt class="descclassname">flask.</tt><tt class="descname">signals_available</tt><a class="headerlink" href="#flask.signals_available" title="Permalink to this definition">¶</a></dt>
<dd><p><cite>True</cite> if the signalling system is available.  This is the case
when <a class="reference external" href="http://pypi.python.org/pypi/blinker">blinker</a> is installed.</p>
</dd></dl>

<dl class="data">
<dt id="flask.template_rendered">
<tt class="descclassname">flask.</tt><tt class="descname">template_rendered</tt><a class="headerlink" href="#flask.template_rendered" title="Permalink to this definition">¶</a></dt>
<dd><p>This signal is sent when a template was successfully rendered.  The
signal is invoked with the instance of the template as <cite>template</cite>
and the context as dictionary (named <cite>context</cite>).</p>
</dd></dl>

<dl class="data">
<dt id="flask.request_started">
<tt class="descclassname">flask.</tt><tt class="descname">request_started</tt><a class="headerlink" href="#flask.request_started" title="Permalink to this definition">¶</a></dt>
<dd><p>This signal is sent before any request processing started but when the
request context was set up.  Because the request context is already
bound, the subscriber can access the request with the standard global
proxies such as <a class="reference internal" href="#flask.request" title="flask.request"><tt class="xref py py-class docutils literal"><span class="pre">request</span></tt></a>.</p>
</dd></dl>

<dl class="data">
<dt id="flask.request_finished">
<tt class="descclassname">flask.</tt><tt class="descname">request_finished</tt><a class="headerlink" href="#flask.request_finished" title="Permalink to this definition">¶</a></dt>
<dd><p>This signal is sent right before the response is sent to the client.
It is passed the response to be sent named <cite>response</cite>.</p>
</dd></dl>

<dl class="data">
<dt id="flask.got_request_exception">
<tt class="descclassname">flask.</tt><tt class="descname">got_request_exception</tt><a class="headerlink" href="#flask.got_request_exception" title="Permalink to this definition">¶</a></dt>
<dd><p>This signal is sent when an exception happens during request processing.
It is sent <em>before</em> the standard exception handling kicks in and even
in debug mode, where no exception handling happens.  The exception
itself is passed to the subscriber as <cite>exception</cite>.</p>
</dd></dl>

<dl class="data">
<dt id="flask.request_tearing_down">
<tt class="descclassname">flask.</tt><tt class="descname">request_tearing_down</tt><a class="headerlink" href="#flask.request_tearing_down" title="Permalink to this definition">¶</a></dt>
<dd><p>This signal is sent when the application is tearing down the request.
This is always called, even if an error happened.  No arguments are
provided.</p>
</dd></dl>

<dl class="class">
<dt id="flask.signals.Namespace">
<em class="property">class </em><tt class="descclassname">flask.signals.</tt><tt class="descname">Namespace</tt><a class="headerlink" href="#flask.signals.Namespace" title="Permalink to this definition">¶</a></dt>
<dd><p>An alias for <a class="reference external" href="http://discorporate.us/projects/Blinker/docs/1.1/api.html#blinker.base.Namespace" title="(in Blinker v1.1)"><tt class="xref py py-class docutils literal"><span class="pre">blinker.base.Namespace</span></tt></a> if blinker is available,
otherwise a dummy class that creates fake signals.  This class is
available for Flask extensions that want to provide the same fallback
system as Flask itself.</p>
<dl class="method">
<dt id="flask.signals.Namespace.signal">
<tt class="descname">signal</tt><big>(</big><em>name</em>, <em>doc=None</em><big>)</big><a class="headerlink" href="#flask.signals.Namespace.signal" title="Permalink to this definition">¶</a></dt>
<dd><p>Creates a new signal for this namespace if blinker is available,
otherwise returns a fake signal that has a send method that will
do nothing but will fail with a <a class="reference external" href="http://docs.python.org/dev/library/exceptions.html#RuntimeError" title="(in Python v3.3)"><tt class="xref py py-exc docutils literal"><span class="pre">RuntimeError</span></tt></a> for all other
operations, including connecting.</p>
</dd></dl>

</dd></dl>

</div>
<div class="section" id="class-based-views">
<h2>Class Based Views<a class="headerlink" href="#class-based-views" title="Permalink to this headline">¶</a></h2>
<p class="versionadded">
<span class="versionmodified">New in version 0.7.</span></p>
<dl class="class">
<dt id="flask.views.View">
<em class="property">class </em><tt class="descclassname">flask.views.</tt><tt class="descname">View</tt><a class="headerlink" href="#flask.views.View" title="Permalink to this definition">¶</a></dt>
<dd><p>Alternative way to use view functions.  A subclass has to implement
<tt class="xref py py-meth docutils literal"><span class="pre">dispatch_request()</span></tt> which is called with the view arguments from
the URL routing system.  If <tt class="xref py py-attr docutils literal"><span class="pre">methods</span></tt> is provided the methods
do not have to be passed to the <a class="reference internal" href="#flask.Flask.add_url_rule" title="flask.Flask.add_url_rule"><tt class="xref py py-meth docutils literal"><span class="pre">add_url_rule()</span></tt></a>
method explicitly:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">class</span> <span class="nc">MyView</span><span class="p">(</span><span class="n">View</span><span class="p">):</span>
    <span class="n">methods</span> <span class="o">=</span> <span class="p">[</span><span class="s">&#39;GET&#39;</span><span class="p">]</span>

    <span class="k">def</span> <span class="nf">dispatch_request</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">name</span><span class="p">):</span>
        <span class="k">return</span> <span class="s">&#39;Hello </span><span class="si">%s</span><span class="s">!&#39;</span> <span class="o">%</span> <span class="n">name</span>

<span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span><span class="s">&#39;/hello/&lt;name&gt;&#39;</span><span class="p">,</span> <span class="n">view_func</span><span class="o">=</span><span class="n">MyView</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span><span class="s">&#39;myview&#39;</span><span class="p">))</span>
</pre></div>
</div>
<p>When you want to decorate a pluggable view you will have to either do that
when the view function is created (by wrapping the return value of
<tt class="xref py py-meth docutils literal"><span class="pre">as_view()</span></tt>) or you can use the <tt class="xref py py-attr docutils literal"><span class="pre">decorators</span></tt> attribute:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">class</span> <span class="nc">SecretView</span><span class="p">(</span><span class="n">View</span><span class="p">):</span>
    <span class="n">methods</span> <span class="o">=</span> <span class="p">[</span><span class="s">&#39;GET&#39;</span><span class="p">]</span>
    <span class="n">decorators</span> <span class="o">=</span> <span class="p">[</span><span class="n">superuser_required</span><span class="p">]</span>

    <span class="k">def</span> <span class="nf">dispatch_request</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
        <span class="o">...</span>
</pre></div>
</div>
<p>The decorators stored in the decorators list are applied one after another
when the view function is created.  Note that you can <em>not</em> use the class
based decorators since those would decorate the view class and not the
generated view function!</p>
<dl class="classmethod">
<dt id="flask.views.View.as_view">
<em class="property">classmethod </em><tt class="descname">as_view</tt><big>(</big><em>name</em>, <em>*class_args</em>, <em>**class_kwargs</em><big>)</big><a class="headerlink" href="#flask.views.View.as_view" title="Permalink to this definition">¶</a></dt>
<dd><p>Converts the class into an actual view function that can be
used with the routing system.  What it does internally is generating
a function on the fly that will instanciate the <tt class="xref py py-class docutils literal"><span class="pre">View</span></tt>
on each request and call the <tt class="xref py py-meth docutils literal"><span class="pre">dispatch_request()</span></tt> method on it.</p>
<p>The arguments passed to <tt class="xref py py-meth docutils literal"><span class="pre">as_view()</span></tt> are forwarded to the
constructor of the class.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.views.View.decorators">
<tt class="descname">decorators</tt><em class="property"> = []</em><a class="headerlink" href="#flask.views.View.decorators" title="Permalink to this definition">¶</a></dt>
<dd><p>The canonical way to decorate class based views is to decorate the
return value of as_view().  However since this moves parts of the
logic from the class declaration to the place where it&#8217;s hooked
into the routing system.</p>
<p>You can place one or more decorators in this list and whenever the
view function is created the result is automatically decorated.</p>
<p class="versionadded">
<span class="versionmodified">New in version 0.8.</span></p>
</dd></dl>

<dl class="method">
<dt id="flask.views.View.dispatch_request">
<tt class="descname">dispatch_request</tt><big>(</big><big>)</big><a class="headerlink" href="#flask.views.View.dispatch_request" title="Permalink to this definition">¶</a></dt>
<dd><p>Subclasses have to override this method to implement the
actual view function code.  This method is called with all
the arguments from the URL rule.</p>
</dd></dl>

<dl class="attribute">
<dt id="flask.views.View.methods">
<tt class="descname">methods</tt><em class="property"> = None</em><a class="headerlink" href="#flask.views.View.methods" title="Permalink to this definition">¶</a></dt>
<dd><p>A for which methods this pluggable view can handle.</p>
</dd></dl>

</dd></dl>

<dl class="class">
<dt id="flask.views.MethodView">
<em class="property">class </em><tt class="descclassname">flask.views.</tt><tt class="descname">MethodView</tt><a class="headerlink" href="#flask.views.MethodView" title="Permalink to this definition">¶</a></dt>
<dd><p>Like a regular class based view but that dispatches requests to
particular methods.  For instance if you implement a method called
<tt class="xref py py-meth docutils literal"><span class="pre">get()</span></tt> it means you will response to <tt class="docutils literal"><span class="pre">'GET'</span></tt> requests and
the <tt class="xref py py-meth docutils literal"><span class="pre">dispatch_request()</span></tt> implementation will automatically
forward your request to that.  Also <tt class="xref py py-attr docutils literal"><span class="pre">options</span></tt> is set for you
automatically:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">class</span> <span class="nc">CounterAPI</span><span class="p">(</span><span class="n">MethodView</span><span class="p">):</span>

    <span class="k">def</span> <span class="nf">get</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
        <span class="k">return</span> <span class="n">session</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="s">&#39;counter&#39;</span><span class="p">,</span> <span class="mi">0</span><span class="p">)</span>

    <span class="k">def</span> <span class="nf">post</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
        <span class="n">session</span><span class="p">[</span><span class="s">&#39;counter&#39;</span><span class="p">]</span> <span class="o">=</span> <span class="n">session</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="s">&#39;counter&#39;</span><span class="p">,</span> <span class="mi">0</span><span class="p">)</span> <span class="o">+</span> <span class="mi">1</span>
        <span class="k">return</span> <span class="s">&#39;OK&#39;</span>

<span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span><span class="s">&#39;/counter&#39;</span><span class="p">,</span> <span class="n">view_func</span><span class="o">=</span><span class="n">CounterAPI</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span><span class="s">&#39;counter&#39;</span><span class="p">))</span>
</pre></div>
</div>
</dd></dl>

</div>
<div class="section" id="url-route-registrations">
<span id="id2"></span><h2>URL Route Registrations<a class="headerlink" href="#url-route-registrations" title="Permalink to this headline">¶</a></h2>
<p>Generally there are three ways to define rules for the routing system:</p>
<ol class="arabic simple">
<li>You can use the <a class="reference internal" href="#flask.Flask.route" title="flask.Flask.route"><tt class="xref py py-meth docutils literal"><span class="pre">flask.Flask.route()</span></tt></a> decorator.</li>
<li>You can use the <a class="reference internal" href="#flask.Flask.add_url_rule" title="flask.Flask.add_url_rule"><tt class="xref py py-meth docutils literal"><span class="pre">flask.Flask.add_url_rule()</span></tt></a> function.</li>
<li>You can directly access the underlying Werkzeug routing system
which is exposed as <a class="reference internal" href="#flask.Flask.url_map" title="flask.Flask.url_map"><tt class="xref py py-attr docutils literal"><span class="pre">flask.Flask.url_map</span></tt></a>.</li>
</ol>
<p>Variable parts in the route can be specified with angular brackets
(<tt class="docutils literal"><span class="pre">/user/&lt;username&gt;</span></tt>).  By default a variable part in the URL accepts any
string without a slash however a different converter can be specified as
well by using <tt class="docutils literal"><span class="pre">&lt;converter:name&gt;</span></tt>.</p>
<p>Variable parts are passed to the view function as keyword arguments.</p>
<p>The following converters are available:</p>
<table border="1" class="docutils">
<colgroup>
<col width="19%" />
<col width="81%" />
</colgroup>
<tbody valign="top">
<tr class="row-odd"><td><cite>unicode</cite></td>
<td>accepts any text without a slash (the default)</td>
</tr>
<tr class="row-even"><td><cite>int</cite></td>
<td>accepts integers</td>
</tr>
<tr class="row-odd"><td><cite>float</cite></td>
<td>like <cite>int</cite> but for floating point values</td>
</tr>
<tr class="row-even"><td><cite>path</cite></td>
<td>like the default but also accepts slashes</td>
</tr>
</tbody>
</table>
<p>Here are some examples:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="nd">@app.route</span><span class="p">(</span><span class="s">&#39;/&#39;</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">index</span><span class="p">():</span>
    <span class="k">pass</span>

<span class="nd">@app.route</span><span class="p">(</span><span class="s">&#39;/&lt;username&gt;&#39;</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">show_user</span><span class="p">(</span><span class="n">username</span><span class="p">):</span>
    <span class="k">pass</span>

<span class="nd">@app.route</span><span class="p">(</span><span class="s">&#39;/post/&lt;int:post_id&gt;&#39;</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">show_post</span><span class="p">(</span><span class="n">post_id</span><span class="p">):</span>
    <span class="k">pass</span>
</pre></div>
</div>
<p>An important detail to keep in mind is how Flask deals with trailing
slashes.  The idea is to keep each URL unique so the following rules
apply:</p>
<ol class="arabic simple">
<li>If a rule ends with a slash and is requested without a slash by the
user, the user is automatically redirected to the same page with a
trailing slash attached.</li>
<li>If a rule does not end with a trailing slash and the user requests the
page with a trailing slash, a 404 not found is raised.</li>
</ol>
<p>This is consistent with how web servers deal with static files.  This
also makes it possible to use relative link targets safely.</p>
<p>You can also define multiple rules for the same function.  They have to be
unique however.  Defaults can also be specified.  Here for example is a
definition for a URL that accepts an optional page:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="nd">@app.route</span><span class="p">(</span><span class="s">&#39;/users/&#39;</span><span class="p">,</span> <span class="n">defaults</span><span class="o">=</span><span class="p">{</span><span class="s">&#39;page&#39;</span><span class="p">:</span> <span class="mi">1</span><span class="p">})</span>
<span class="nd">@app.route</span><span class="p">(</span><span class="s">&#39;/users/page/&lt;int:page&gt;&#39;</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">show_users</span><span class="p">(</span><span class="n">page</span><span class="p">):</span>
    <span class="k">pass</span>
</pre></div>
</div>
<p>This specifies that <tt class="docutils literal"><span class="pre">/users/</span></tt> will be the URL for page one and
<tt class="docutils literal"><span class="pre">/users/page/N</span></tt> will be the URL for page <cite>N</cite>.</p>
<p>Here are the parameters that <a class="reference internal" href="#flask.Flask.route" title="flask.Flask.route"><tt class="xref py py-meth docutils literal"><span class="pre">route()</span></tt></a> and
<a class="reference internal" href="#flask.Flask.add_url_rule" title="flask.Flask.add_url_rule"><tt class="xref py py-meth docutils literal"><span class="pre">add_url_rule()</span></tt></a> accept.  The only difference is that
with the route parameter the view function is defined with the decorator
instead of the <cite>view_func</cite> parameter.</p>
<table border="1" class="docutils">
<colgroup>
<col width="21%" />
<col width="79%" />
</colgroup>
<tbody valign="top">
<tr class="row-odd"><td><cite>rule</cite></td>
<td>the URL roule as string</td>
</tr>
<tr class="row-even"><td><cite>endpoint</cite></td>
<td>the endpoint for the registered URL rule.  Flask itself
assumes that the name of the view function is the name
of the endpoint if not explicitly stated.</td>
</tr>
<tr class="row-odd"><td><cite>view_func</cite></td>
<td>the function to call when serving a request to the
provided endpoint.  If this is not provided one can
specify the function later by storing it in the
<a class="reference internal" href="#flask.Flask.view_functions" title="flask.Flask.view_functions"><tt class="xref py py-attr docutils literal"><span class="pre">view_functions</span></tt></a> dictionary with the
endpoint as key.</td>
</tr>
<tr class="row-even"><td><cite>defaults</cite></td>
<td>A dictionary with defaults for this rule.  See the
example above for how defaults work.</td>
</tr>
<tr class="row-odd"><td><cite>subdomain</cite></td>
<td>specifies the rule for the subdomain in case subdomain
matching is in use.  If not specified the default
subdomain is assumed.</td>
</tr>
<tr class="row-even"><td><cite>**options</cite></td>
<td>the options to be forwarded to the underlying
<a class="reference external" href="http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Rule" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">Rule</span></tt></a> object.  A change to
Werkzeug is handling of method options.  methods is a list
of methods this rule should be limited to (<cite>GET</cite>, <cite>POST</cite>
etc.).  By default a rule just listens for <cite>GET</cite> (and
implicitly <cite>HEAD</cite>).  Starting with Flask 0.6, <cite>OPTIONS</cite> is
implicitly added and handled by the standard request
handling.  They have to be specified as keyword arguments.</td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="view-function-options">
<span id="view-func-options"></span><h2>View Function Options<a class="headerlink" href="#view-function-options" title="Permalink to this headline">¶</a></h2>
<p>For internal usage the view functions can have some attributes attached to
customize behavior the view function would normally not have control over.
The following attributes can be provided optionally to either override
some defaults to <a class="reference internal" href="#flask.Flask.add_url_rule" title="flask.Flask.add_url_rule"><tt class="xref py py-meth docutils literal"><span class="pre">add_url_rule()</span></tt></a> or general behavior:</p>
<ul class="simple">
<li><cite>__name__</cite>: The name of a function is by default used as endpoint.  If
endpoint is provided explicitly this value is used.  Additionally this
will be prefixed with the name of the blueprint by default which
cannot be customized from the function itself.</li>
<li><cite>methods</cite>: If methods are not provided when the URL rule is added,
Flask will look on the view function object itself is an <cite>methods</cite>
attribute exists.  If it does, it will pull the information for the
methods from there.</li>
<li><cite>provide_automatic_options</cite>: if this attribute is set Flask will
either force enable or disable the automatic implementation of the
HTTP <cite>OPTIONS</cite> response.  This can be useful when working with
decorators that want to customize the <cite>OPTIONS</cite> response on a per-view
basis.</li>
</ul>
<p>Full example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">def</span> <span class="nf">index</span><span class="p">():</span>
    <span class="k">if</span> <span class="n">request</span><span class="o">.</span><span class="n">method</span> <span class="o">==</span> <span class="s">&#39;OPTIONS&#39;</span><span class="p">:</span>
        <span class="c"># custom options handling here</span>
        <span class="o">...</span>
    <span class="k">return</span> <span class="s">&#39;Hello World!&#39;</span>
<span class="n">index</span><span class="o">.</span><span class="n">provide_automatic_options</span> <span class="o">=</span> <span class="bp">False</span>
<span class="n">index</span><span class="o">.</span><span class="n">methods</span> <span class="o">=</span> <span class="p">[</span><span class="s">&#39;GET&#39;</span><span class="p">,</span> <span class="s">&#39;OPTIONS&#39;</span><span class="p">]</span>

<span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span><span class="s">&#39;/&#39;</span><span class="p">,</span> <span class="n">index</span><span class="p">)</span>
</pre></div>
</div>
<p class="versionadded">
<span class="versionmodified">New in version 0.8: </span>The <cite>provide_automatic_options</cite> functionality was added.</p>
</div>
</div>


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  <h3><a href="index.html">Table Of Contents</a></h3>
  <ul>
<li><a class="reference internal" href="#">API</a><ul>
<li><a class="reference internal" href="#application-object">Application Object</a></li>
<li><a class="reference internal" href="#blueprint-objects">Blueprint Objects</a></li>
<li><a class="reference internal" href="#incoming-request-data">Incoming Request Data</a></li>
<li><a class="reference internal" href="#response-objects">Response Objects</a></li>
<li><a class="reference internal" href="#sessions">Sessions</a></li>
<li><a class="reference internal" href="#session-interface">Session Interface</a></li>
<li><a class="reference internal" href="#test-client">Test Client</a></li>
<li><a class="reference internal" href="#application-globals">Application Globals</a></li>
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<li><a class="reference internal" href="#message-flashing">Message Flashing</a></li>
<li><a class="reference internal" href="#returning-json">Returning JSON</a></li>
<li><a class="reference internal" href="#template-rendering">Template Rendering</a></li>
<li><a class="reference internal" href="#configuration">Configuration</a></li>
<li><a class="reference internal" href="#extensions">Extensions</a></li>
<li><a class="reference internal" href="#useful-internals">Useful Internals</a></li>
<li><a class="reference internal" href="#signals">Signals</a></li>
<li><a class="reference internal" href="#class-based-views">Class Based Views</a></li>
<li><a class="reference internal" href="#url-route-registrations">URL Route Registrations</a></li>
<li><a class="reference internal" href="#view-function-options">View Function Options</a></li>
</ul>
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