Inheritance destroying data in original model

[leandropls]

I've created the following model:

school/models.py:

from django.contrib.auth.models import User
(...)
class Parent(User):
    contract = models.ForeignKey(Contract)
    user = models.OneToOneField(User, parent_link = True, related_name = 'school_parent')

Now I'm trying to "promote" a regular django user into a school parent:

>>> from django.contrib.auth.models import User
>>> from school.models import Parent, Contract
>>> u = User(username = 'myuser')
>>> u.save()
>>> User.objects.all()
[<User: myuser>]
>>> c = Contract.objects.get(pk = 1)
>>> p = Parent(user = u, contract = c)
>>> p.save()
>>> User.objects.all()
[<User: >]
>>> 

Apparently, in "Parent" creation, the user "myuser" is being destroyed. Django docs show that you can "attach" one model to other via OneToOneField the way I'm doing. It also says that multi-table inheritance automatically creates a OneToOneField. But as I inherit from User and set its OneToOneField to an existing instance of the user, the specified existing instance gets destroyed. The expected result was that django simply made the association.

[sargikk]

Another example with same problem when OneToOneField related to the inherited model.

from django.contrib.auth.models import User
(...)
class PersonUser(User):
    name = models.CharField(max_length=255)
    surname = models.CharField(max_length=255)

class OnetoOneToUser(Model):
    user = models.OneToOneField(Parent, blank=True, null=True)
    info = models.CharField(max_length=255, default='some parent info')

>>> person_user = PersonUser(username = 'first_user', name='1', surname='1')
>>> person_user.save()
>>> User.objects.all()
[<User: first_user>]
>>> one_to_one = OnetoOneToUser(user=person_user)
>>> one_to_one.save()
>>> person_user_2 = PersonUser(username = 'second_user', name='1', surname='1')
>>> person_user_2.save()
>>> User.objects.all() 
[<User: second_user>]

[leandropls]

Replying to sargikk:

What's the state of User.objects.all() after one_to_one.save()?

[Aymeric Augustin]

This appears to be the same problem as #7623.