Generate Production-Ready FastAPI Endpoints

This skill generates robust, production-ready FastAPI endpoints with proper validation, error handling, documentation, and security. Core principles: type safety first via Pydantic models for every request/response, correct HTTP status codes per scenario, comprehensive error handling with meaningful messages, clear OpenAPI documentation with examples, authentication/authorization patterns where needed, and attention to async/await and database connection handling for performance.

Use it when a FastAPI endpoint needs typed request/response validation, structured error responses, and OpenAPI documentation built in from the start, not just a bare @app.get returning a dict.

class UserCreate(BaseModel):
    email: EmailStr
    name: str = Field(..., min_length=1, max_length=100)

@app.post("/users/", response_model=UserResponse, status_code=status.HTTP_201_CREATED)
async def create_user(user_data: UserCreate, db: Session = Depends(get_db)):
    existing_user = db.query(User).filter(User.email == user_data.email).first()
    if existing_user:
        raise HTTPException(status_code=409, detail="User with this email already exists")
    db_user = User(**user_data.dict())
    db.add(db_user)
    db.commit()
    return db_user

CRUD patterns cover create (with a duplicate-email 409 check and rollback on failure), read-by-ID (404 on missing) and paginated list (skip/limit query params with validation bounds), and update with an authorization check comparing the current user to the resource owner or admin flag. Authentication uses HTTPBearer security with a get_current_user dependency that decodes and validates a JWT, raising 401 on failure; authorization then compares that resolved user against the request. Global exception handlers catch ValueError (mapped to a structured 400) and any uncaught Exception (mapped to a generic 500), both returning a consistent {"detail": ..., "error_code": ...} shape. Advanced patterns include a file-upload endpoint validating content type and a 5MB size limit, and a background-task endpoint that queues an email notification via BackgroundTasks and returns immediately. Configuration is centralized in a Pydantic Settings class reading from a .env file (database URL, secret key, JWT algorithm, token expiry).

Python developers building FastAPI services who want typed, documented, production-ready CRUD endpoints - with authentication, file uploads, and background tasks - generated consistently rather than hand-written per route. Best practices tie it together: use dependency injection for database sessions and shared logic, validate early with Pydantic Field validators, return the status code that matches the operation (201 for creation, 204 for deletion), include response examples in the OpenAPI docs, group endpoints with OpenAPI tags so the generated documentation stays organized as the API grows, and add a health-check endpoint so the service can be monitored the same way any other production endpoint would be.