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<div class="section" id="working-with-the-shell">
<span id="shell"></span><h1>Working with the Shell<a class="headerlink" href="#working-with-the-shell" title="Permalink to this headline">¶</a></h1>
<p class="versionadded">
<span class="versionmodified">New in version 0.3.</span></p>
<p>One of the reasons everybody loves Python is the interactive shell. It
basically allows you to execute Python commands in real time and
immediately get results back. Flask itself does not come with an
interactive shell, because it does not require any specific setup upfront,
just import your application and start playing around.</p>
<p>There are however some handy helpers to make playing around in the shell a
more pleasant experience. The main issue with interactive console
sessions is that you’re not triggering a request like a browser does which
means that <a class="reference internal" href="api.html#flask.g" title="flask.g"><tt class="xref py py-data docutils literal"><span class="pre">g</span></tt></a>, <a class="reference internal" href="api.html#flask.request" title="flask.request"><tt class="xref py py-data docutils literal"><span class="pre">request</span></tt></a> and others are not
available. But the code you want to test might depend on them, so what
can you do?</p>
<p>This is where some helper functions come in handy. Keep in mind however
that these functions are not only there for interactive shell usage, but
also for unittesting and other situations that require a faked request
context.</p>
<p>Generally it’s recommended that you read the <a class="reference internal" href="reqcontext.html#request-context"><em>The Request Context</em></a>
chapter of the documentation first.</p>
<div class="section" id="creating-a-request-context">
<h2>Creating a Request Context<a class="headerlink" href="#creating-a-request-context" title="Permalink to this headline">¶</a></h2>
<p>The easiest way to create a proper request context from the shell is by
using the <a class="reference internal" href="api.html#flask.Flask.test_request_context" title="flask.Flask.test_request_context"><tt class="xref py py-attr docutils literal"><span class="pre">test_request_context</span></tt></a> method which creates
us a <a class="reference internal" href="api.html#flask.ctx.RequestContext" title="flask.ctx.RequestContext"><tt class="xref py py-class docutils literal"><span class="pre">RequestContext</span></tt></a>:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><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>
</pre></div>
</div>
<p>Normally you would use the <cite>with</cite> statement to make this request object
active, but in the shell it’s easier to use the
<a class="reference internal" href="api.html#flask.ctx.RequestContext.push" title="flask.ctx.RequestContext.push"><tt class="xref py py-meth docutils literal"><span class="pre">push()</span></tt></a> and
<a class="reference internal" href="api.html#flask.ctx.RequestContext.pop" title="flask.ctx.RequestContext.pop"><tt class="xref py py-meth docutils literal"><span class="pre">pop()</span></tt></a> methods by hand:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">ctx</span><span class="o">.</span><span class="n">push</span><span class="p">()</span>
</pre></div>
</div>
<p>From that point onwards you can work with the request object until you
call <cite>pop</cite>:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">ctx</span><span class="o">.</span><span class="n">pop</span><span class="p">()</span>
</pre></div>
</div>
</div>
<div class="section" id="firing-before-after-request">
<h2>Firing Before/After Request<a class="headerlink" href="#firing-before-after-request" title="Permalink to this headline">¶</a></h2>
<p>By just creating a request context, you still don’t have run the code that
is normally run before a request. This might result in your database
being unavailable if you are connecting to the database in a
before-request callback or the current user not being stored on the
<a class="reference internal" href="api.html#flask.g" title="flask.g"><tt class="xref py py-data docutils literal"><span class="pre">g</span></tt></a> object etc.</p>
<p>This however can easily be done yourself. Just call
<a class="reference internal" href="api.html#flask.Flask.preprocess_request" title="flask.Flask.preprocess_request"><tt class="xref py py-meth docutils literal"><span class="pre">preprocess_request()</span></tt></a>:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><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="gp">>>> </span><span class="n">ctx</span><span class="o">.</span><span class="n">push</span><span class="p">()</span>
<span class="gp">>>> </span><span class="n">app</span><span class="o">.</span><span class="n">preprocess_request</span><span class="p">()</span>
</pre></div>
</div>
<p>Keep in mind that the <a class="reference internal" href="api.html#flask.Flask.preprocess_request" title="flask.Flask.preprocess_request"><tt class="xref py py-meth docutils literal"><span class="pre">preprocess_request()</span></tt></a> function
might return a response object, in that case just ignore it.</p>
<p>To shutdown a request, you need to trick a bit before the after request
functions (triggered by <a class="reference internal" href="api.html#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>) operate on
a response object:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">app</span><span class="o">.</span><span class="n">process_response</span><span class="p">(</span><span class="n">app</span><span class="o">.</span><span class="n">response_class</span><span class="p">())</span>
<span class="go"><Response 0 bytes [200 OK]></span>
<span class="gp">>>> </span><span class="n">ctx</span><span class="o">.</span><span class="n">pop</span><span class="p">()</span>
</pre></div>
</div>
<p>The functions registered as <a class="reference internal" href="api.html#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> are
automatically called when the context is popped. So this is the perfect
place to automatically tear down resources that were needed by the request
context (such as database connections).</p>
</div>
<div class="section" id="further-improving-the-shell-experience">
<h2>Further Improving the Shell Experience<a class="headerlink" href="#further-improving-the-shell-experience" title="Permalink to this headline">¶</a></h2>
<p>If you like the idea of experimenting in a shell, create yourself a module
with stuff you want to star import into your interactive session. There
you could also define some more helper methods for common things such as
initializing the database, dropping tables etc.</p>
<p>Just put them into a module (like <cite>shelltools</cite> and import from there):</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">from</span> <span class="nn">shelltools</span> <span class="kn">import</span> <span class="o">*</span>
</pre></div>
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<h3><a href="index.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">Working with the Shell</a><ul>
<li><a class="reference internal" href="#creating-a-request-context">Creating a Request Context</a></li>
<li><a class="reference internal" href="#firing-before-after-request">Firing Before/After Request</a></li>
<li><a class="reference internal" href="#further-improving-the-shell-experience">Further Improving the Shell Experience</a></li>
</ul>
</li>
</ul>
<h3>Related Topics</h3>
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<li><a href="index.html">Documentation overview</a><ul>
<li>Previous: <a href="extensions.html" title="previous chapter">Flask Extensions</a></li>
<li>Next: <a href="patterns/index.html" title="next chapter">Patterns for Flask</a></li>
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