Flask app route decorator URL variable URL converter HTTP methods request args request form request JSON response tuple jsonify

render_template Jinja variable Jinja condition Jinja loop template inheritance include template custom filter static file URL flash message redirect with url_for

application factory blueprint blueprint prefix application context request context g object before_request after_request teardown_request custom CLI command

session secure cookie config secret key CSRF concept password hashing login-required decorator authorization check file upload validation safe filename security headers

abort 404 handler 500 handler custom exception make_response cookies FileResponse equivalent send_file send_from_directory streaming response conditional response

database connection SQLAlchemy session concept transaction boundary pagination external API request email integration background job concept cache integration WebSocket extension concept configuration classes

test client application fixture request context test JSON endpoint test form POST test session test CLI runner mock external API error handler test coverage workflow

debug mode safety environment config logging proxy fix WSGI server Gunicorn workers health endpoint readiness endpoint graceful shutdown deployment checklist