mirror of https://github.com/pallets/flask.git
91 lines
3.3 KiB
ReStructuredText
91 lines
3.3 KiB
ReStructuredText
.. _tutorial-setup:
|
|
|
|
Step 2: Application Setup Code
|
|
==============================
|
|
|
|
Now that we have the schema in place we can create the application module.
|
|
Let's call it `flaskr.py` inside the `flaskr` folder. For starters we
|
|
will add the imports we will need as well as the config section. For
|
|
small applications it's a possibility to drop the configuration directly
|
|
into the module which we will be doing here. However a cleaner solution
|
|
would be to create a separate `.ini` or `.py` file and load that or import
|
|
the values from there.
|
|
|
|
In `flaskr.py`::
|
|
|
|
# all the imports
|
|
import sqlite3
|
|
from flask import Flask, request, session, g, redirect, url_for, \
|
|
abort, render_template, flash
|
|
|
|
# configuration
|
|
DATABASE = '/tmp/flaskr.db'
|
|
DEBUG = True
|
|
SECRET_KEY = 'development key'
|
|
USERNAME = 'admin'
|
|
PASSWORD = 'default'
|
|
|
|
Next we can create our actual application and initialize it with the
|
|
config from the same file, in `flaskr.py`::
|
|
|
|
# create our little application :)
|
|
app = Flask(__name__)
|
|
app.config.from_object(__name__)
|
|
|
|
:meth:`~flask.Config.from_object` will look at the given object (if it's a
|
|
string it will import it) and then look for all uppercase variables
|
|
defined there. In our case, the configuration we just wrote a few lines
|
|
of code above. You can also move that into a separate file.
|
|
|
|
Usually, it is a good idea to load a configuration from a configurable
|
|
file. This is what :meth:`~flask.Config.from_envvar` can do, replacing the
|
|
:meth:`~flask.Config.from_object` line above::
|
|
|
|
app.config.from_envvar('FLASKR_SETTINGS', silent=True)
|
|
|
|
That way someone can set an environment variable called
|
|
:envvar:`FLASKR_SETTINGS` to specify a config file to be loaded which will then
|
|
override the default values. The silent switch just tells Flask to not complain
|
|
if no such environment key is set.
|
|
|
|
The `secret_key` is needed to keep the client-side sessions secure.
|
|
Choose that key wisely and as hard to guess and complex as possible. The
|
|
debug flag enables or disables the interactive debugger. *Never leave
|
|
debug mode activated in a production system*, because it will allow users to
|
|
execute code on the server!
|
|
|
|
We also add a method to easily connect to the database specified. That
|
|
can be used to open a connection on request and also from the interactive
|
|
Python shell or a script. This will come in handy later.
|
|
|
|
::
|
|
|
|
def connect_db():
|
|
return sqlite3.connect(app.config['DATABASE'])
|
|
|
|
Finally we just add a line to the bottom of the file that fires up the
|
|
server if we want to run that file as a standalone application::
|
|
|
|
if __name__ == '__main__':
|
|
app.run()
|
|
|
|
With that out of the way you should be able to start up the application
|
|
without problems. Do this with the following command::
|
|
|
|
python flaskr.py
|
|
|
|
You will see a message telling you that server has started along with
|
|
the address at which you can access it.
|
|
|
|
When you head over to the server in your browser you will get an 404
|
|
page not found error because we don't have any views yet. But we will
|
|
focus on that a little later. First we should get the database working.
|
|
|
|
.. admonition:: Externally Visible Server
|
|
|
|
Want your server to be publicly available? Check out the
|
|
:ref:`externally visible server <public-server>` section for more
|
|
information.
|
|
|
|
Continue with :ref:`tutorial-dbinit`.
|