Django Inheritance gives import errors

Question

I have one class (DeckDeviceUtil) with an abstract function (get_active_deckdevices) who needs to be inherited by 2 classes (Deck and Device). The structure is as follows:

A.py

from models import Deck
    class DeckDeviceUtil:
        @property
        @abstractmethod
        def deckdevice(self):
            pass

        def get_active_deckdevices(self):
            #somecode

    class Device(models.Model, DeckDeviceUtil):
        #somecode

    class DeckDevice(models.Model):
        #uses Deck

B.py

from backend.devices.models import DeckDeviceUtil

class Deck(models.Model, DeckDeviceUtil):
    #somecode

I get following error:

from backend.house.models import Deck
ImportError: cannot import name 'Deck'

probably because the 2 python files/classes need each other. When I try to do the imports inside the classes there are other errors

when import DeckDeviceUtil inside Deck :

class Deck(models.Model, DeckDeviceUtil):
NameError: name 'DeckDeviceUtil' is not defined

when import Deck inside Device:

from backend.house.models import Deck
ImportError: cannot import name 'Deck'

Important: Device needs to import Deck

What's the best way to solve this?

You are making a cyclic import. You thus should break the cycle. — Willem Van Onsem, Mar 18 '20 at 19:50
Does this answer your question? [Circular (or cyclic) imports in Python](https://stackoverflow.com/questions/744373/circular-or-cyclic-imports-in-python) — Brian61354270, Mar 18 '20 at 19:51
Why do you import `Deck` in the file where you define `DeckDeviceUtil` and `Device`? — Iain Shelvington, Mar 18 '20 at 21:05
@IainShelvington the DeckDevice classe uses this. I added to the code. Sorry for that — sg_sg94, Mar 18 '20 at 23:21
Can you show where it's used? If it's used in a foreign key you can reference it using a string to prevent circular imports — Iain Shelvington, Mar 19 '20 at 00:44
@IainShelvington if I put it in brackets I get "ValueError: Related model 'Deck' cannot be resolved" — sg_sg94, Mar 19 '20 at 08:46

Django Inheritance gives import errors

0 Answers0