#23465: Inheritance destroying data in original model
-------------------------------------+-------------------------------------
Reporter: leandropls | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.6
(models, ORM) | Resolution:
Severity: Normal | Triage Stage:
Keywords: | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Description changed by leandropls:
Old description:
> I've created the following model:
>
> school/models.py:
> {{{#!python
> 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:
>
> {{{#!python
> >>> 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[1] 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[2]. 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.
New description:
I've created the following model:
school/models.py:
{{{#!python
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:
{{{#!python
>>> 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.
--
--
Ticket URL: <https://code.djangoproject.com/ticket/23465#comment:3>
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