Union typing on model property

[LukasBerka]

Describe the bug
The resolve_type_hint method inside plumbing.py does not recognize a hint in form:

def my_model_method(self) -> Union[None, OtherType]:
    pass

because the resolve_type_hint checks specifically for isinstance(None, args[1]).
on line 834.

so the same method with switched types in Union does work as expected

def my_model_method(self) -> Union[OtherType, None]:
    pass

Using
Python 3.9
drf-spectacular == 0.13.1
djangorestframework == 3.12.2

Expected behavior
I would assume that the order of types in Union does not matter as Python documentation says.
https://docs.python.org/3/library/typing.html#typing.Union

[tfranzel]

certainly a bug or rather incomplete parsing. the rationale behind it was that this gets automatically translated Optional[OtherType] -> Union[OtherType, None].

[tfranzel]

closing this issue for now. feel free to comment if anything is missing or not working and we will follow-up.