python type_error ai_generated true

pydantic.errors.PydanticUserError: @field_validator 'check_email' 应为 classmethod 或 staticmethod。请用 @classmethod 或 @staticmethod 包装。

pydantic.errors.PydanticUserError: @field_validator 'check_email' should be a classmethod or a staticmethod. Wrap the function with @classmethod or @staticmethod.

ID: python/pydantic-field-validator-signature-error

其他格式: JSON · Markdown 中文 · English
80%修复率
90%置信度
0证据数
2024-03-15首次发现

版本兼容性

版本状态引入弃用备注
2.x active — — —

根因分析

在 Pydantic v2 中，@field_validator 必须装饰 classmethod（或 staticmethod）。缺少 @classmethod 装饰器会在类定义时引发 PydanticUserError。

English

In Pydantic v2, @field_validator must decorate a classmethod (or staticmethod). Missing the @classmethod decorator causes a PydanticUserError at class definition time.

generic

解决方案

  1. 98% 成功率 
    from pydantic import BaseModel, field_validator

class User(BaseModel):
    email: str

    @field_validator('email')
    @classmethod
    def check_email(cls, v):
        assert '@' in v
        return v
  2. 95% 成功率 
    from pydantic import BaseModel, field_validator

class User(BaseModel):
    email: str

    @field_validator('email')
    @staticmethod
    def check_email(v):
        return v.lower()

无效尝试

常见但无效的做法:

  1. 80% 失败

    Decorator order matters: @field_validator must be the outermost decorator, i.e., listed first.

  2. 60% 失败

    @validator is deprecated in v2 and raises PydanticDeprecatedSince20 warnings; it also still requires classmethod semantics.