Casting Types With MyPy
Typing in Python is not yet very mature. This small example displays several issues:
if request.user.is_authenticated:
return JsonResponse(
{
"user": {
"uid": request.user.uid,
"username": request.user.username,
"email": request.user.email,
}
}
)
The original type of request.user is Union[AbstractBaseUser, AnonymousUser] (which itself is already wrong; the user is actually a Django model that inherits from AbstractBaseUser, not AbstractBaseUser). MyPy doesn’t understand that is_authenticated narrows the options, you need to do it manually using casting.
Here’s the final, working code:
if request.user.is_authenticated:
user = cast(User, request.user)
return JsonResponse(
{
"user": {
"uid": user.uid,
"username": user.username,
"email": user.email,
}
}
)