Pydantic：如何使用一个字段的值来设置其他字段的值？

Question

我有什么

词典：

user_dict = {'user': {'field1': 'value1',
                      'field2': 'value2'},
             'admin':{'field1': 'value3',
                      'field2': 'value4'}}

金字塔模型：

class User(BaseModel):
    account_type: Optional[str] = 'user'
    field1: Optional[str] = ''
    field1: Optional[str] = ''

    class Config:
        validate_assignment = True

    @validator("account_type", pre=True, always=True)
        def _set_account_type(cls, account_type: str):
        return account_type or "user"

所需结果

我想根据account_type从user_dict查找field1和field2的值。因此，我应该能够执行以下操作：

user = User()
print(user.field1)
# > 'value1'

print(user.field2)
# > 'value2'

user2 = User(field1=None, field2=None)
print(user2.field1)
# > 'value1'

print(user2.field2)
# > 'value2'

user3 = User(field1='other_field1', field2='other_field2')
print(user2.field1)
# > 'other_field1'

print(user2.field2)
# > 'other_field2'

我尝试过的事情

class User(BaseModel):
    account_type: Optional[str] = 'user'
    field1: Optional[str] = user_dict['account_type']['field1']
    field1: Optional[str] = user_dict['account_type']['field2']

    class Config:
        validate_assignment = True

    @validator("account_type", pre=True, always=True)
        def _set_account_type(cls, account_type: str):
        return account_type or "user"

user = User()
print(user.field1)
# > 'value1'

user = User(field1=None)
print(user.field1)
# > None

为字段1和字段2使用验证器：

class User(BaseModel):
    account_type: Optional[str] = 'user'
    field1: Optional[str]
    field1: Optional[str]

    class Config:
        validate_assignment = True

    @validator("account_type", pre=True, always=True)
        def _set_account_type(cls, account_type: str):
        return account_type or "user"
    
    @validator("field1", pre=True, always=True)
        def _set_plan_credits(cls, value):
            if value is None:
                value = 'value1'
        return user_dict['account_type']['field1'] or value

    @validator("field2", pre=True, always=True)
        def _set_rollover_credits(cls, value):
            if value is None:
                value = 'value2'
        return user_dict['account_type']['field2'] or value

user = User()
# > AttributeError: type object 'Account' has no attribute 'account_type'

关于我可以做什么以获得预期结果的任何想法？

Answer 1

我使用 root_validator 装饰器解决了这个问题，如下所示：

解决方案：

@root_validator(pre=False)
def _set_fields(cls, values: dict) -> dict:
    """This is a validator that sets the field values based on the
    the user's account type.

    Args:
        values (dict): Stores the attributes of the User object.

    Returns:
        dict: The attributes of the user object with the user's fields.
    """
    values["field1"] = user_dict[values["account_type"]]["field1"]
    values["field2"] = user_dict[values["account_type"]]["field2"]
    return values