Flask Foundations

Flask is a micro-framework, but professional applications require structure to remain maintainable.

Application Factory Pattern

Avoid global app objects. Instead, use a function to create the application instance.

• Benefits: Easier testing (multiple app instances), better configuration management, and avoidance of circular imports.
• Pattern: def create_app(config_class=Config): ...

Blueprints

Organize your application into distinct components (e.g., auth, api, main).

• Registration: app.register_blueprint(auth_bp, url_prefix='/auth')
• Utility: Keeps codebases modular and allows for shared middleware/filters per component.

Best Practices

• Environment Config: Use a Config class and python-dotenv for sensitive keys.
• Lifecycle: Understand before_request, after_request, and teardown_appcontext.