fastapi-templates

Organize code into layers: api/ for routes, services/ for business logic, repositories/ for data access, models/ for SQLAlchemy tables, and schemas/ for Pydantic validation. This separation keeps route handlers thin and makes each layer independently testable.

Create an async engine with create_async_engine and an AsyncSession factory, then expose a get_db dependency that yields sessions with automatic commit, rollback, and close handling. Inject it into routes using Depends(get_db).

FastAPI provides OAuth2PasswordBearer for token extraction but not JWT encoding itself. Combine it with python-jose for token signing and passlib with bcrypt for password hashing, as shown in the security module.

Override the get_db dependency using app.dependency_overrides to inject a session backed by in-memory SQLite via aiosqlite. Then use httpx AsyncClient with pytest-asyncio fixtures to run requests against the app.

Common pitfalls include calling synchronous database drivers inside async handlers, putting business logic directly in route functions, and failing to properly manage session lifecycles. Use async drivers throughout and delegate logic to a service layer.