flask skill

Overview

This skill provides practical, hands-on guidance for building web applications with the Flask framework. It covers routing, templates, forms, database integration, common extensions, and deployment patterns. Use it to accelerate development, avoid common pitfalls, and follow modern Flask conventions.

How this skill works

The skill explains core Flask concepts and shows how to set up projects, define routes, render templates with Jinja2, and handle form submissions. It walks through integrating databases (SQLAlchemy, Flask-Migrate), using extensions (Flask-Login, Flask-WTF), testing, and deploying to popular hosts. Each topic includes concrete code patterns and configuration tips you can apply directly.

When to use it

• Starting a new Python web app or prototype that needs lightweight, flexible routing
• Adding form handling, validation, and user authentication to an existing project
• Connecting a Flask app to a SQL database and managing schema migrations
• Choosing deployment options like Gunicorn + Nginx, Docker, or PaaS platforms
• Learning best practices for structuring Flask applications and writing tests

Best practices

• Use application factory and Blueprints to keep code modular and testable
• Manage configuration per environment and never store secrets in source control
• Validate user input with Flask-WTF and use CSRF protection for forms
• Use SQLAlchemy + Flask-Migrate for schema migrations and ORM patterns
• Serve production apps with a WSGI server (Gunicorn) behind a reverse proxy (Nginx)

Example use cases

• Create a blog with routes for posts, templates for views, and a PostgreSQL backend
• Add user registration and login using Flask-Login and secure password hashing
• Build AJAX endpoints that return JSON for a single-page frontend
• Containerize a Flask app with Docker and deploy it to a cloud provider
• Write unit and integration tests for route handlers and database operations

FAQ