Flask User Authentication: Implementing Permission Control with Flask-Login

This article introduces how to implement user authentication and permission control for web applications using Flask-Login. The core steps include: first, installing necessary libraries such as Flask, Flask-Login, Flask-SQLAlchemy, and Werkzeug. Configure the application and user model, define a User class inheriting from UserMixin, storing username, password hash, and role fields (with password encrypted using Werkzeug). Set up the user loading function to load users from the database via @login_manager.user_loader. Implement login and logout functions: verify username and password during login, then use login_user to maintain the session; use logout_user for logout. Protect routes with the @login_required decorator, and further control permissions through the role field. Key considerations: passwords must be stored encrypted, SECRET_KEY should be securely configured, and ensure the user loading function works correctly. The implementation ultimately achieves user session maintenance, route permission control, and basic role validation, with extensibility for features like "Remember Me" and OAuth.