Python Entity or ID Pattern

usage.py

def my_fun(user_or_id: UserOrId):
   user = get_user(user_or_id)
   
   # Do something with user
  
   
# These both do the same thing (but the first avoids the extra db hit)
my_fun(user)
my_fun(user.id)

user_service.py

from typing import cast, overload
from uuid import UUID


@overload
def get_user(user_or_id: User) -> User:
    ...


@overload
def get_user(user_or_id: UUID) -> User:
    ...


UserOrId = User | UUID


def get_user(user_or_id):
    if isinstance(user_or_id, User):
        return user_or_id

    return cast(User, User.objects.get(id=user_or_id))