Problem with model inheritance when parent has relation to self

[osanha@…]

Test models:

class Parent(models.Model):
    s = models.ForeignKey('self', null=True, blank=True)
    a = models.TextField()
    
class Child(Parent):
    b = models.TextField()

Test session:

>>> child = Child.objects.create(a='parent field', b='child field')
>>> child.delete()
Traceback (most recent call last):
...
ProgrammingError:  "s_id" column is not exist at "forums_child" relation.

These error was begined at 0.97-pre-SVN-8007
as I know, previous version is not shown these errors.

[Sanha]

Is it related with 'newforms-admin' ?
​http://code.djangoproject.com/changeset/7964

[Russell Keith-Magee]

Duplicate of #6755.

[Sanha]

I think that second issue is valid.

when parent model has foreign key to self, delete child (or parent) object was failed because finding parent's foreign key.

see below.

class Parent(models.Model):
    s = models.ForeignKey('self', null=True, blank=True)
# or same:  s = models.ForeignKey('Parent', null=True, blank=True)
    a = models.TextField()
    
class Child(Parent):
    b = models.TextField()

python shell

>>> child = Child.objects.create(a='parent field', b='child field')
>>> child.delete()
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/usr/lib64/python2.5/site-packages/django/db/models/base.py", line 423, in delete
    delete_objects(seen_objs)
  File "/usr/lib64/python2.5/site-packages/django/db/models/query.py", line 836, in delete_objects
    update_query.clear_related(field, pk_list)
  File "/usr/lib64/python2.5/site-packages/django/db/models/sql/subqueries.py", line 211, in clear_related
    self.execute_sql(None)
  File "/usr/lib64/python2.5/site-packages/django/db/models/sql/subqueries.py", line 112, in execute_sql
    super(UpdateQuery, self).execute_sql(result_type)
  File "/usr/lib64/python2.5/site-packages/django/db/models/sql/query.py", line 1608, in execute_sql
    cursor.execute(sql, params)
  File "/usr/lib64/python2.5/site-packages/django/db/backends/util.py", line 18, in execute
    return self.cursor.execute(sql, params)
ProgrammingError:  "s_id" column is not exist at "forums_child" relation.

[charmless]

Marking a ticket as a Duplicate means the problem is known and being worked on at another ticket. It is not meant to imply that a problem isn't valid (if it were, the duplicate would be closed too :) )

For browsers: Duplicate of #6755.

[Russell Keith-Magee]

Replying to charmless:

Marking a ticket as a Duplicate means the problem is known and being worked on at another ticket. It is not meant to imply that a problem isn't valid (if it were, the duplicate would be closed too :) )

In this case, it looks like the reporter has put two issues in a single ticket (which, by the way, is very bad form). The first issue (inheritance doesn't work in admin) is clearly a duplicate of #6755. The second part of the report isn't obviously a duplicate, so it requires independent verification.

I've updated the ticket title and description to describe the problem better.

[Russell Keith-Magee]

Test case demonstrating problem

[Russell Keith-Magee]

The failure occurs when an update call is made to clear the foreign key, but the update call assumes the foreign key is on the child class, not the parent. The action is correct; the SQL that is generate is not. The solution isn't immediately obvious to me, so I've uploaded the test case in case someone else gets to this problem first.

[Malcolm Tredinnick]

Fixed in [8128].

[Jacob]

Milestone 1.0 beta deleted