What is Flask? When to use
Learn Flask from scratch to advanced: setup, routing, templates, database, auth, testing, security, and deployment.
Environment Setup Basics
Use a virtual environment and pin dependencies for stable deployments.
- 1 Create venv:
python -m venv .venv - 2 Activate venv and install framework.
- 3 Run a minimal server and verify output.
Create a Project Structure
Use a clean structure: app/ (core code), tests/, config, and a single entry file.
Routing URLs
Define routes, validate input, and return consistent responses.
Handlers / Controllers Logic
Keep request handlers thin. Put business logic in services that can be tested without HTTP.
Templates HTML rendering
If you render HTML, use templates + layout inheritance and serve static assets correctly.
Database Persistence
Pick one DB and one ORM/tooling approach. Add migrations early.
Authentication Sessions/JWT
Add auth only after your core routes work. Keep password hashing and secret management correct.
Testing Unit + integration
Write unit tests for services, and integration tests for critical endpoints.
Security Basics
Validate inputs, sanitize outputs, set security headers, and rate limit where required.
Deployment Production
Separate dev/prod config, run behind a reverse proxy, and enable logging/monitoring.
Advanced Topics Scale
Focus on performance profiling, async/background jobs, caching, and clean architecture.