python type_error ai_generated true

pydantic.error_wrappers.ValidationError: 1 validation error for ResponseModel value is not a valid dict

ID: python/fastapi-response-model-mismatch

Also available as: JSON · Markdown · 中文
80%Fix Rate
84%Confidence
0Evidence
2024-05-12First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.x active — — —

Root Cause

Response model expects a dict but function returns a different type (e.g., list or string).

generic

中文

响应模型期望字典，但函数返回了其他类型（如列表或字符串）。

Workarounds

  1. 95% success 
    Ensure return type matches response_model: @app.get('/item', response_model=Item)
async def get_item() -> Item:
    return Item(name='test', price=10.0)
  2. 85% success 
    Use response_model_exclude_unset=True to allow missing fields: @app.get('/item', response_model=Item, response_model_exclude_unset=True)

Dead Ends

Common approaches that don't work:

  1. 60% fail

    Loses type safety and may cause runtime errors downstream.

  2. 70% fail

    May not match model fields exactly; still validation error.