python data_error ai_generated true

fastapi.exceptions.RequestValidationError: field required

ID: python/fastapi-request-validation-missing-field

Also available as: JSON · Markdown · 中文
80%Fix Rate
88%Confidence
0Evidence
2024-05-20First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.x active — — —

Root Cause

Request body or query parameters missing a required field defined in Pydantic model or function signature.

generic

中文

请求体或查询参数缺少 Pydantic 模型或函数签名中定义的必填字段。

Workarounds

  1. 95% success 
    from fastapi import FastAPI, Request
from fastapi.exceptions import RequestValidationError
from fastapi.responses import JSONResponse

@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request: Request, exc: RequestValidationError):
    return JSONResponse(status_code=422, content={"detail": exc.errors()})
  2. 90% success 
    Ensure required fields in Pydantic model: class Item(BaseModel):
    name: str  # no default
    price: float

Dead Ends

Common approaches that don't work:

  1. 80% fail

    FastAPI raises RequestValidationError specifically; generic catches miss it and return 500.

  2. 70% fail

    Hides bugs and may not satisfy API contract; still fails if type mismatch.