RootCauseunvalidated
FastAPI's request-body parsing and Pydantic model validation are tied to the declared model type; excluding fields at the annotation/body level does not reliably integrate with Pydantic's normal model construction and validation flow. Using private/hidden fields is the intended Pydantic mechanism, but `Field()` cannot be used with private attributes in Pydantic v2.
75caa3e0-1012-4e63-ad5f-384842dcf304
FastAPI's request-body parsing and Pydantic model validation are tied to the declared model type; excluding fields at the annotation/body level does not reliably integrate with Pydantic's normal model construction and validation flow. Using private/hidden fields is the intended Pydantic mechanism, but Field() cannot be used with private attributes in Pydantic v2.