Gutes Error Handling = gute DX. Der Client muss wissen, was passiert ist, warum und was er dagegen tun kann.

Error-Response-Format¶

// RFC 7807 — Problem Details { “type”: “https://api.example.com/errors/validation”, “title”: “Validation Error”, “status”: 422, “detail”: “Request body contains invalid fields”, “instance”: “/api/users”, “errors”: [ { “field”: “email”, “message”: “Invalid email format” }, { “field”: “age”, “message”: “Must be positive” } ] }

Implementierung¶

FastAPI¶

from fastapi import HTTPException class AppError(HTTPException): def __init__(self, code: str, message: str, status: int = 400, details=None): super().__init__(status_code=status, detail={ “code”: code, “message”: message, “details”: details or [] }) @app.exception_handler(AppError) async def app_error_handler(request, exc): return JSONResponse(status_code=exc.status_code, content=exc.detail)

Wichtigste Erkenntnis¶

RFC 7807 für standardisiertes Error-Format. Immer Code + Message + Details. Auf dem Server loggen, nicht beim Client.