Basic App

The sample code below illustrates the power of using Flask-User with sensible defaults: With just a dozen lines of additional code, a basic Flask application can be transformed to offer the following features:

  • Register with username and email
  • Email confirmation
  • Login with username or email, Logout
  • Protect pages from unauthenticated access
  • Change username
  • Change password
  • Forgot password

Single-file techniques

To keep the examples simple, we are using some unusual single-file techniques:
- Using class based configuration instead of file based configuration
- Using render_template_string() instead of render_template()
- Placing everything in one file

None of these techniques are recommended outside of tutorial usage.

Setup a development environment

These tutorials assume that you are working with virtualenv and virtualenvwrapper and that the code resides in ~/dev/example:

# Create virtualenv 'example'
mkvirtualenv example

# Install required Python packages in the 'example' virtualenv
workon example
pip install flask-user
pip install flask-mail

# Change working directory
mkdir -p ~dev/example
cd ~/dev/example                # or C:\dev\example on Windows

Create the basic_app.py file

Create ~/dev/example/basic_app.py with the content below.

Make sure to replace the following settings:
MAIL_USERNAME = 'email@example.com‘
MAIL_PASSWORD = ‘password’
MAIL_DEFAULT_SENDER = ‘“Sender” <noreply@example.com>’
MAIL_SERVER = ‘smtp.gmail.com’
MAIL_PORT = 465
MAIL_USE_SSL = True
MAIL_USE_TLS = False
with settings that are appropriate for your SMTP server.

Highlighted lines shows the lines added to a basic Flask application.

Run the Basic App

Run the Basic App with the following command:

cd ~/dev/example
python basic_app.py

And point your browser to http://localhost:5000.

Troubleshooting

If you receive an SendEmailError message, or if the Registration form does not respond quickly then you may have specified incorrect SMTP settings.

If you receive a ‘AssertionError: No sender address has been set’ error, you may be using an old version of Flask-Mail which uses DEFAULT_MAIL_SENDER instead of MAIL_DEFAULT_SENDER.

If you receive a SQLAlchemy error message, delete the basic_app.sqlite file and restart the app. You may be using an old DB schema in that file.