Return proxied class in many to many relation, Django 2.0

Question

From another installed app, I have models like this

class Organization(model.Model):
    name = models.CharField(max_length=255, blank=True)

class Person(model.Model):
    name = models.CharField(max_length=255, blank=True)

class Membership(model.Model):

    organization = models.ForeignKey(
        Organization,
        related_name='memberships',
        # memberships will go away if the org does
        on_delete=models.CASCADE,
        help_text="A link to the Organization in which the Person is a member.")

    person = models.ForeignKey(
        Person,
        related_name='memberships',
        null=True,
        # Membership will just unlink if the person goes away
        on_delete=models.SET_NULL,
        help_text="A link to the Person that is a member of the Organization.")

In my app, I need to add some method to some of the models. So I have a model like

class ProxiedOrganization(other_app.models.Organization):
    class Meta:
        proxy = True

    special_attribute = 'foo'


class ProxiedPerson(other_app.models.Person):
    class Meta:
        proxy = True

    def special_method(self):
         print('I do something special')

When I get the memberships from an organization, they are of type other_app.models.Person.

> type(proxied_org_instance.memberships[0].person)
<class 'other_app.models.Person'>

but, I'd like them to be my instances of my proxy class

> type(proxied_org_instance.memberships[0].person)
<class 'my_app.models.ProxiedPerson'>

Is there a good way of doing this? Is this the kind of thing that I can do with a query manager? The solution must work for Django 2.0.

Answer 1

I adapted Matt Schinckel's work on overriding proxy model relations, for a solution that will work with Django 2.0 and 2.1. The code is available as a library on pypi.