Generate Production-Ready FastAPI Endpoints

FastAPI Endpoint Generator specializes in generating robust, production-ready FastAPI API endpoints with proper validation, error handling, documentation, and security practices. Core principles: type safety first via Pydantic models for request and response validation, appropriate HTTP status codes per scenario, comprehensive error handling with meaningful messages, clear OpenAPI documentation with examples, authentication and authorization patterns when needed, and async/await plus database connection handling for performance.

Use it to generate FastAPI endpoint code: Pydantic request, response, and error models; CRUD endpoints, CREATE with duplicate and error handling, READ with pagination, UPDATE with authorization checks, using SQLAlchemy Session dependency injection; bearer-token authentication with a get_current_user dependency; exception-handler middleware for ValueError and general exceptions; file-upload endpoints with content-type and size validation; background-task endpoints; and Pydantic-based settings configuration loaded from a .env file. It is specific to FastAPI's dependency-injection and Pydantic patterns, not a generic REST framework generator for Flask, Django REST Framework, or Express.

Input is an API endpoint requirement - resource type, CRUD operations needed, authentication requirements, and any file or background-task handling. Output is FastAPI endpoint code: Pydantic models using BaseModel with Field validators, EmailStr, and Config.from_attributes; route handlers decorated with response_model, status_code, summary, and a responses dict documenting each status code; Depends()-injected database sessions and current-user authentication; HTTPException raises with the correct status code and detail message; @app.exception_handler middleware; file-upload and background-task endpoint patterns; and a pydantic.BaseSettings configuration class.

@app.post("/users/", 
          response_model=UserResponse, 
          status_code=status.HTTP_201_CREATED,
          summary="Create a new user",
          responses={
              201: {"description": "User created successfully"},
              400: {"model": ErrorResponse, "description": "Invalid input data"},
              409: {"model": ErrorResponse, "description": "User already exists"}
          })
async def create_user(
    user_data: UserCreate,
    db: Session = Depends(get_db)
):
    # Check if user exists
    existing_user = db.query(User).filter(User.email == user_data.email).first()
    if existing_user:
        raise HTTPException(
            status_code=status.HTTP_409_CONFLICT,
            detail="User with this email already exists"
        )
    
    try:
        db_user = User(**user_data.dict())
        db.add(db_user)
        db.commit()
        db.refresh(db_user)
        return db_user
    except Exception as e:
        db.rollback()
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail="Failed to create user"
        )

Documented dependencies include FastAPI's own Depends, HTTPException, status, UploadFile/File, and BackgroundTasks; SQLAlchemy Session for database access; Pydantic for models and BaseSettings; and fastapi.security.HTTPBearer for bearer-token authentication. Best practices call for dependency injection for shared logic, async/await for I/O, request/response middleware for CORS and rate limiting, OpenAPI tags for endpoint organization, and health-check endpoints for monitoring.

Backend developers building FastAPI services who want production-ready endpoint code with proper validation, status codes, error handling, authentication, and OpenAPI documentation generated consistently, rather than writing each endpoint's boilerplate from scratch.