How to use Django model inheritance with signals?

Question

I have a few model inheritance levels in Django:

class WorkAttachment(models.Model):
    \"\"\" Abstract class that holds all fields that are required in eac         


        

Answer 1

I just did this using python's (relatively) new __init_subclass__ method:

from django.db import models

def perform_on_save(*args, **kw):
    print("Doing something important after saving.")

class ParentClass(models.Model):
    class Meta:
        abstract = True

    @classmethod
    def __init_subclass__(cls, **kwargs):
        super().__init_subclass__(**kwargs)
        models.signals.post_save.connect(perform_on_save, sender=cls)

class MySubclass(ParentClass):
    pass  # signal automatically gets connected.

This requires django 2.1 and python 3.6 or better. Note that the @classmethod line seems to be required when working with the django model and associated metaclass even though it's not required according to the official python docs.