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38. Appendix

Best Practices

• Use APIRouter to organize endpoints by domain
• Separate models (schemas), services, and routes
• Use dependency injection for DB sessions, auth, and config
• Always validate input with Pydantic models
• Use response_model to control output
• Set up CORS explicitly for production
• Use environment variables for configuration
• Add logging and request ID middleware

Interview Questions

1. What is FastAPI and how does it differ from Flask?
2. Explain the role of Pydantic in FastAPI.
3. How does FastAPI handle async requests?
4. What is dependency injection in FastAPI?
5. How do you validate query parameters?
6. Explain the lifespan protocol.
7. How would you mount a Flask app inside FastAPI?
8. What is CORS and how do you configure it?
9. How do you handle database sessions in FastAPI?
10. What are WebSockets and how do you implement them?

Glossary

Term	Definition
ASGI	Asynchronous Server Gateway Interface — standard for async Python web apps
WSGI	Web Server Gateway Interface — synchronous standard (Flask, Django)
Pydantic	Data validation library using Python type annotations
OpenAPI	Standard API specification format (formerly Swagger)
Starlette	ASGI framework that FastAPI is built on
Uvicorn	ASGI server for running FastAPI