当类型实际上正确时如何修复 MyPy [返回值] 错误

Question

我正在使用 Django-Ninja + MyPy，我收到此错误，它收到的类型为 tuple[int, dict[str, str]]" 不正确，因为它与 tuple[int, None 之一不匹配] | tuple[int, DetailType] 类型，但它与第二种类型完全相同，因为在代码的其他部分，它可以正确地计算出它具有 "detail" 。但一旦我使用 Union[...] 它就无法递归地查找？

apps/users/views.py:106: error: Incompatible return value type (got "tuple[int, Message]", expected "tuple[int, None] | tuple[int, DetailType]")  [return-value]

这就是我的类型的样子：

DetailType = TypedDict("DetailType", {"detail": str})
MessageType = tuple[int, DetailType]
NoContentType = tuple[int, None]

这是 mypy 返回错误的完整代码：

@post("me/password/change/", response={204: None, 401: Message}, url_name="users_me_password_change")
def change_password(request: HttpRequest, data: ChangePasswordRequest) -> Union[NoContentType, MessageType]: <<< THIS IS RETURN TYPE
    user = request.user
    if not user.check_password(data.password):
        return 401, {"detail": "Password is incorrect."} <<< IN THIS LINE IS MYPY ERROR
    user.set_password(data.new_password)
    user.save()
    return 204, None

Answer 1

您需要明确告诉 MyPy 您的

MessageType

是一个带有整数状态代码和

DetailType

的元组，其中

DetailType

是

TypedDict

。但是，当您直接在 return 语句中使用

dict[str, str]

时，就会出现问题，该语句不会自动识别为与您的

DetailType

兼容。

这是解决此问题的解决方案：

• 确保您的返回值与定义的类型完全匹配。
• 确保在返回值中显式使用

  DetailType

  。

更新代码：

from typing import TypedDict, Union

# Define the types
DetailType = TypedDict("DetailType", {"detail": str})
MessageType = tuple[int, DetailType]
NoContentType = tuple[int, None]

# Define the function with the return type hint
@post("me/password/change/", response={204: None, 401: Message}, url_name="users_me_password_change")
def change_password(request: HttpRequest, data: ChangePasswordRequest) -> Union[NoContentType, MessageType]:
    user = request.user
    if not user.check_password(data.password):
        # Use the correct MessageType here, which expects a dict[str, str] under "detail"
        return 401, {"detail": "Password is incorrect."}  # This should be fine now
    user.set_password(data.new_password)
    user.save()
    return 204, None