Python Web Development with Flask

This repository contains the source code that I demonstrated in my O'Reilly webcast Python Web Development with Flask.

Requirements

To install and run this application you need:

• Python 2.7 or 3.3+
• virtualenv (not required if you are using Python 3.4)
• git (only to clone this repository)

Installation

The commands below install the application and its dependencies:

$ git clone https://github.com/miguelgrinberg/flask-webcast.git
$ cd flask-webcast
$ virtualenv venv
$ . venv/bin/activate
(venv) pip install -r requirements.txt

Note for Python 3.4 users: replace virtualenv with pyvenv.

Note for Microsoft Windows users: replace the virtual environment activation command above with venv\Scripts\activate.

Running

This project is composed of five different applications located in sub-directories named as follows:

• 01-hello-world
• 02-templates
• 03-forms
• 04-database
• 05-structure

To run applications one through four you have to cd into the directory and run the hello.py script in it. For example:

(venv) $ cd 01-hello-world
(venv) $ python hello.py

For the fourth application you need to set up a Mongo database before you can use the application. The connection URL to this database must be stored in a MONGO_URI environment variable. For the live demonstration in the webcast a free cloud based database from http://mongohq.com was used, this is a good alternative if you don't want to go through the effort of installing the database server on your computer.

The fifth application is started by running a script called manage.py. Before you run the application you need to select which configuration to run, which can be development or production. Depending on the selected configuration a second environment variable configures the Mongo database. To run the server in development mode you can run the following commands in a bash shell:

(venv) $ cd 05-structure
(venv) $ FLASK_CONFIG=development MONGO_DEV_URI=http://<your-mongodb-url-here> python manage.py runserver

If you are doing this on Windows then the commands are as follows:

(venv) $ cd 05-structure
(venv) $ set FLASK_CONFIG=development
(venv) $ set MONGO_DEV_URI=http://<your-mongodb-uri-here>
(venv) $ python manage.py runserver

Note that when running the application in production mode the Mongo URL is specified in the MONGO_URI environment variable. Different variables are used for each mode to allow all modes to be configured in the same computer.

Once the server starts you can open http://localhost:5000 in your web browser to see the application in action. To stop the application use Ctrl+C.

See the webcast for a live demonstration.

Unit tests

The fifth version of the application can also run unit tests. The command to run them is as follows:

(venv) $ MONGO_TEST_URI=http://<your-mongodb-test-uri_here> python manage.py test
test_app_exists (test_basics.BasicsTestCase) ... ok
test_app_is_testing (test_basics.BasicsTestCase) ... ok
test_names (test_basics.BasicsTestCase) ... ok

Name               Stmts   Miss Branch BrMiss  Cover   Missing
--------------------------------------------------------------
app                   10      0      0      0   100%
app.hello              3      0      0      0   100%
app.hello.routes      12      0      4      0   100%
--------------------------------------------------------------
TOTAL                 25      0      4      0   100%
----------------------------------------------------------------------
Ran 3 tests in 9.338s

OK

If you are using Windows then the equivalent commands are:

(venv) $ set MONGO_TEST_URI=http://<your-mongodb-test-uri-here>
(venv) $ python manage.py test

It is recommended that you use a different database for testing.

After the tests run you can see a coverage report. This gives you an idea of how much of the application code the tests touch.