python data_error ai_generated true

pydantic_core._pydantic_core.ValidationError: 1 validation error for User email Field required [type=missing, input_value={'name': 'Alice'}, input_type=dict]

ID: python/pydantic-validationerror-missing-field

Also available as: JSON · Markdown · 中文
80%Fix Rate
88%Confidence
0Evidence
2024-03-12First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
2.x active — — —

Root Cause

A required field without a default value is absent from the input payload passed to the model constructor.

generic

中文

模型中存在无默认值的必填字段，但传入构造函数的输入数据缺少该字段。

Workarounds

  1. 95% success 
    class User(BaseModel):
    name: str
    email: str = ""
# or use a default factory for mutable types
from pydantic import Field
class User(BaseModel):
    tags: list[str] = Field(default_factory=list)
  2. 92% success 
    from typing import Optional
class User(BaseModel):
    email: Optional[str] = None
  3. 88% success 
    payload = {"name": "Alice"}
payload.setdefault("email", "[email protected]")
user = User(**payload)

Dead Ends

Common approaches that don't work:

  1. 85% fail

    Swallowing the exception leaves the object unconstructed or partially populated, causing AttributeError downstream and hiding the real data problem.

  2. 70% fail

    In Pydantic v2, Optional without a default is still required; validation still fails with the same missing error.

  3. 90% fail

    extra='allow' only permits additional keys; it does not supply values for missing required fields.