diff options
Diffstat (limited to 'studio/static/doc/flask-docs/_sources/tutorial/dbinit.txt')
| -rw-r--r-- | studio/static/doc/flask-docs/_sources/tutorial/dbinit.txt | 67 |
1 files changed, 0 insertions, 67 deletions
diff --git a/studio/static/doc/flask-docs/_sources/tutorial/dbinit.txt b/studio/static/doc/flask-docs/_sources/tutorial/dbinit.txt deleted file mode 100644 index b546a1a..0000000 --- a/studio/static/doc/flask-docs/_sources/tutorial/dbinit.txt +++ /dev/null @@ -1,67 +0,0 @@ -.. _tutorial-dbinit: - -Step 3: Creating The Database -============================= - -Flaskr is a database powered application as outlined earlier, and more -precisely, an application powered by a relational database system. Such -systems need a schema that tells them how to store that information. So -before starting the server for the first time it's important to create -that schema. - -Such a schema can be created by piping the `schema.sql` file into the -`sqlite3` command as follows:: - - sqlite3 /tmp/flaskr.db < schema.sql - -The downside of this is that it requires the sqlite3 command to be -installed which is not necessarily the case on every system. Also one has -to provide the path to the database there which leaves some place for -errors. It's a good idea to add a function that initializes the database -for you to the application. - -If you want to do that, you first have to import the -:func:`contextlib.closing` function from the contextlib package. If you -want to use Python 2.5 it's also necessary to enable the `with` statement -first (`__future__` imports must be the very first import):: - - from __future__ import with_statement - from contextlib import closing - -Next we can create a function called `init_db` that initializes the -database. For this we can use the `connect_db` function we defined -earlier. Just add that function below the `connect_db` function:: - - def init_db(): - with closing(connect_db()) as db: - with app.open_resource('schema.sql') as f: - db.cursor().executescript(f.read()) - db.commit() - -The :func:`~contextlib.closing` helper function allows us to keep a -connection open for the duration of the `with` block. The -:func:`~flask.Flask.open_resource` method of the application object -supports that functionality out of the box, so it can be used in the -`with` block directly. This function opens a file from the resource -location (your `flaskr` folder) and allows you to read from it. We are -using this here to execute a script on the database connection. - -When we connect to a database we get a connection object (here called -`db`) that can give us a cursor. On that cursor there is a method to -execute a complete script. Finally we only have to commit the changes. -SQLite 3 and other transactional databases will not commit unless you -explicitly tell it to. - -Now it is possible to create a database by starting up a Python shell and -importing and calling that function:: - ->>> from flaskr import init_db ->>> init_db() - -.. admonition:: Troubleshooting - - If you get an exception later that a table cannot be found check that - you did call the `init_db` function and that your table names are - correct (singular vs. plural for example). - -Continue with :ref:`tutorial-dbcon` |