python-fastapi-expert

Structure a scalable FastAPI backend using Router-Service-Repository layers to separate concerns. Routers handle HTTP requests, services contain business logic, and repositories manage database operations, maintaining clean architecture with strong typing throughout the async API project.

Implement dependency injection in FastAPI using the Depends function to provide database sessions and repositories to route handlers. This async-first approach ensures non-blocking I/O and cleanly separates database integration logic from business logic across the Router-Service-Repository architecture.

Use SQLModel and SQLAlchemy with FastAPI by defining Pydantic-compatible database models and running Alembic migrations. This integration provides async database access, automatic OpenAPI documentation updates, and typed schema validation across the API's data models.

FastAPI automatically generates OpenAPI documentation and Swagger UI from your strongly typed Pydantic models and route definitions. The framework ensures correct API docs are always up to date, reflecting changes in data models and endpoint definitions without manual intervention.

Handle HTTP exceptions properly in a FastAPI application by enforcing proper HTTP exception handling within the service layer of your Router-Service-Repository architecture. This ensures consistent error responses, maintains clean separation of concerns, and integrates with CI linting for robust API validation.

You can use Alembic migrations with FastAPI and SQLModel to manage database schema changes. This setup supports async I/O operations and ensures database integration remains synchronized with SQLAlchemy models, providing reliable version control for your API's data layer.