82 lines
3 KiB
ReStructuredText
82 lines
3 KiB
ReStructuredText
.. _tutorial-setup:
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Step 2: Application Setup Code
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==============================
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Now that we have the schema in place, we can create the application module.
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Let's call it `flaskr.py` inside the `flaskr` folder. For starters, we
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will add the required imports as well as the config section. For
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small applications, such as this, the configuration can be dropped directly
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into the application module. However, a cleaner solution would be to create
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a separate `.ini` or `.py` file and load that or import the values from there.
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::
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# all the imports
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import sqlite3
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from flask import Flask, request, session, g, redirect, url_for, \
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abort, render_template, flash
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# configuration
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DATABASE = '/tmp/flaskr.db'
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DEBUG = True
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SECRET_KEY = 'development key'
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USERNAME = 'admin'
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PASSWORD = 'default'
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Next we can create our actual application and initialize it with the
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config from the same file::
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# create our little application :)
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app = Flask(__name__)
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app.config.from_object(__name__)
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:meth:`~flask.Config.from_object` will look at the given object (if it's a
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string it will import it) and then look for all uppercase variables
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defined there. In our case, :meth:`~flask.Config.from_object` finds the
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configuration we just wrote a few lines of code above.
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It is also a good idea to be able to load a configuration from a
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configurable file. This is the purpose of :meth:`~flask.Config.from_envvar`::
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app.config.from_envvar('FLASKR_SETTINGS', silent=True)
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That way someone can set an environment variable called
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:envvar:`FLASKR_SETTINGS` to specify a config file to be loaded which will
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then override the default values. The silent switch just tells Flask to
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not complain if no such environment key is set.
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The `secret_key` is needed to keep the client-side sessions secure.
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Choose that key wisely and as hard to guess and complex as possible. The
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debug flag enables or disables the interactive debugger. Never leave
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debug mode activated in a production system because it will allow users to
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execute code on the server!
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We also add a method to easily connect to the database specified. That
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can be used to open a connection on request and also from the interactive
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Python shell or a script. This will come in handy later.
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::
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def connect_db():
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return sqlite3.connect(app.config['DATABASE'])
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Finally, we add a line to the bottom of the file that fires up the
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server if we want to run that file as a standalone application::
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if __name__ == '__main__':
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app.run()
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With that out of the way you should be able to start up the application.
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When you head over to your web browser you will get a 404
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page not found error because we don't have any views yet. Not to worry,
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we'll create some views in a bit. But first we should get the database
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working.
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.. admonition:: Externally Visible Server
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Want your server to be publicly available? Check out the
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:ref:`externally visible server <public-server>` section for more
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information.
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Continue with :ref:`tutorial-dbinit`.
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