Django: Two different child classes point to same parent class

Question

I have a model Person which stores all data about people. I also have a Client model which extends Person. I have another extending model OtherPe

Answer 1

As mentioned in a comment already, there is an open ticket for this very question: https://code.djangoproject.com/ticket/7623

In the meanwhile there is a proposed patch (https://github.com/django/django/compare/master...ar45:child_object_from_parent_model) which not using obj.__dict__ but creates an dictionary with all field values cycling over all fields. Here a simplified function:

def create_child_from_parent_model(parent_obj, child_cls, init_values: dict):
    attrs = {}
    for field in parent_obj._meta._get_fields(reverse=False, include_parents=True):
        if field.attname not in attrs:
            attrs[field.attname] = getattr(parent_obj, field.attname)
    attrs[child_cls._meta.parents[parent_obj.__class__].name] = parent_obj
    attrs.update(init_values)
    print(attrs)
    return child_cls(**attrs)

person = Person.objects.get(id=)
client = create_child_from_parent_model(person, Client, {})
client.save()

If you want to create a sibling:

client_person = getattr(person, person._meta.parents.get(Person).name)
other_person = create_child_from_parent_model(person, OhterPerson, {})
other_person.save()

This method has the advantage that methods that are overwritten by the child are not replaced by the original parent methods. For me using the original answers obj.__dict__.update() led to exceptions as I was using the FieldTracker from model_utils in the parent class.