Flask Before Request: Authentication & More

The 'before_request' function is a powerful Flask hook that executes before every incoming request. It's ideal for performing actions such as user authentication, populating templates with user data, logging requests, and other essential tasks.

Here's a basic example demonstrating how to use 'before_request' to implement authentication:

@app.before_request
def before_request():
    print('Checks for authentication')
    if not session.get('logged_in'):
        return redirect(url_for('login'))

In this example, every request is checked for an active session. If the user is not logged in ('logged_in' session variable is missing), they're redirected to the login page.