带有变量的Pydantic (文字，==，eq=)

Question

如何使用pydantic来要求我的对象具有一个由变量设置的精确数值？

from pydantic import BaseModel, Field

var = 10.0

class Group(BaseModel):
     value: Literal[var] # something like this
     value: float = Field(..., eq=var) # or this

此外，创建使用变量的pydantic类的最佳方法是什么？是否有一种方法可以在类(而不是工厂)中进行验证，以便使用同一个类来验证不同的值？

from typing import Literal, TypeVar
from pydantic import BaseModel, Field

TGroup = TypeVar("TGroup", bound="Group") # does not work

def factory(var: float) -> TGroup: 
    class Group(BaseModel):
        value: Literal[var]
    return Group

# instead do something like this
class Group(BaseModel):
    def __init__(self, var: float, **data) -> None:
        self.value: str = Field(..., regex=f'{var}')
        super().__init__(**data)

obj = {'value': 10}
Group(var=10, **obj) # does not work

Answer 1

您可以使用validator来验证传递的值。

下面是您的代码可能是什么样子。不过，我对同名的两个变量有疑问.

from pydantic import BaseModel, ValidationError, validator

val: float = 10.0

class Group(BaseModel):
     # Are you sure you can have to variables with the same name?
     value: Literal[var] # something like this
     value: float

    @validator('value')
    def check_value(cls, v):
        if v == val:
            return v

        raise ValueError(f'Value must be equal to {val}')

这里是官方文件

https://pydantic-docs.helpmanual.io/usage/validators/