id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
13203	Deletion error of model with generic relation to inherited model	ramusus	nobody	"I found that if we have 2 simple models connected by GenericRelation:

{{{
from django.contrib.comments.models import Comment
class NewComment(Comment):
    title = models.CharField(max_length=60)

class PersonWithComments(models.Model):
    comments = generic.GenericRelation(NewComment, object_id_field='object_pk')
}}}

It's impossible to delete PersonWithComments instance. With postgresql_psycopg2 and mysql DB drivers I always get error: 

{{{
Traceback (most recent call last):
  File ""/home/ram/PycharmProjects/m/web_site/generic/tests.py"", line 75, in test_inherited_models_delete
    p.delete()
  File ""/home/ram/PycharmProjects/m/web_site/django/db/models/base.py"", line 610, in delete
    delete_objects(seen_objs, using)
  File ""/home/ram/PycharmProjects/m/web_site/django/db/models/query.py"", line 1282, in delete_objects
    del_query.delete_batch_related(pk_list, using=using)
  File ""/home/ram/PycharmProjects/m/web_site/django/db/models/sql/subqueries.py"", line 69, in delete_batch_related
    self.do_query(f.m2m_db_table(), where, using=using)
  File ""/home/ram/PycharmProjects/m/web_site/django/db/models/sql/subqueries.py"", line 27, in do_query
    self.get_compiler(using).execute_sql(None)
  File ""/home/ram/PycharmProjects/m/web_site/django/db/models/sql/compiler.py"", line 727, in execute_sql
    cursor.execute(sql, params)
  File ""/home/ram/PycharmProjects/m/web_site/django/db/backends/postgresql_psycopg2/base.py"", line 44, in execute
    return self.cursor.execute(query, args)
DatabaseError: column ""object_pk"" does not exist
LINE 1: DELETE FROM ""generic_newcomment"" WHERE (""object_pk"" IN (E'23...
}}}

With sqlite3 everithing is ok! I don't know, may be this issue related to http://code.djangoproject.com/ticket/11263, but there tells nothing about deleting.

This error appears because fields 'object_pk' and 'content_type' are not in NewComment, they are in Comment model from Comments app. And there is no checks for these fields inside ContentTypes apps. 

I attach tests for recreating this issue and patch for solving it.
"	Bug	closed	contrib.contenttypes	1.1	Normal	fixed	content_type	ramusus@…	Ready for checkin	1	0	0	0	0	0