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
20002	Model inheritance depth may result in invalid SQL queries	Keryn Knight <django@…>	nobody	"This is an example pulled out of the test case I was writing as a baseline for something kind of crazy, and on '''1.4''' to boot.

Using
{{{
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': None,
    }
}
}}}
for settings (to get an in-memory database for tests), and the following models:
{{{
class A(Model):
    subcontent_type = models.ForeignKey(ContentType, null=True, related_name='+',
                                        editable=False)
    objects = Manager()

    def __unicode__(self):
        return unicode(self.pk)

    class Meta:
        ordering = ('pk',)

class B(A): pass
class C(B): pass
class D(C): pass
}}}
The following test case fails at evaluating D:
{{{
from django.test import TestCase as DjangoTestCase

class PolymorphTestCase(DjangoTestCase):
    def setUp(self):
        self.objects = [A.objects.create(), B.objects.create(),
                        C.objects.create(), D.objects.create(),
                        C.objects.create(), B.objects.create()]

    def test_default_manager(self):
        with self.assertNumQueries(4):
            all = list(A.objects.all())
            self.assertEqual(all, [
                A(pk=1), A(pk=2), A(pk=3), A(pk=4), A(pk=5), A(pk=6),
            ])
            all = list(B.objects.all())
            self.assertEqual(all, [
                B(pk=2), B(pk=3), B(pk=4), B(pk=5), B(pk=6),
            ])

            all = list(C.objects.all())
            self.assertEqual(all, [C(pk=3), C(pk=4), C(pk=5)])

            import pdb; pdb.set_trace()
            all = list(D.objects.all())
            self.assertEqual(all, [D(pk=4)])
}}}

The stack trace is:
{{{
Traceback (most recent call last):
  File ""/path/to/tests.py"", line 411, in test_default_manager
    all = list(D.objects.all())
  File ""/path/python2.7/site-packages/Django-1.4.5-py2.7.egg/django/db/models/query.py"", line 87, in __len__
    self._result_cache.extend(self._iter)
  File ""/path/python2.7/site-packages/Django-1.4.5-py2.7.egg/django/db/models/query.py"", line 291, in iterator
    for row in compiler.results_iter():
  File ""/path/python2.7/site-packages/Django-1.4.5-py2.7.egg/django/db/models/sql/compiler.py"", line 763, in results_iter
    for rows in self.execute_sql(MULTI):
  File ""/path/python2.7/site-packages/Django-1.4.5-py2.7.egg/django/db/models/sql/compiler.py"", line 818, in execute_sql
    cursor.execute(sql, params)
  File ""/path/python2.7/site-packages/Django-1.4.5-py2.7.egg/django/db/backends/util.py"", line 40, in execute
    return self.cursor.execute(sql, params)
  File ""/path/python2.7/site-packages/Django-1.4.5-py2.7.egg/django/db/backends/sqlite3/base.py"", line 344, in execute
    return Database.Cursor.execute(self, query, params)
DatabaseError: no such column: T5.a_ptr_id
}}}

the query used for D.objects.all() is:
{{{
'SELECT ""testmodel_a"".""id"", ""testmodel_a"".""subcontent_type_id"", ""testmodel_b"".""a_ptr_id"", ""testmodel_c"".""b_ptr_id"", ""testmodel_d"".""c_ptr_id"" FROM ""testmodel_d"" INNER JOIN ""testmodel_a"" ON (""testmodel_d"".""c_ptr_id"" = ""testmodel_a"".""id"") INNER JOIN ""testmodel_b"" ON (""testmodel_d"".""c_ptr_id"" = ""testmodel_b"".""a_ptr_id"") INNER JOIN ""testmodel_c"" ON (""testmodel_d"".""c_ptr_id"" = ""testmodel_c"".""b_ptr_id"") INNER JOIN ""testmodel_a"" T6 ON (T5.""a_ptr_id"" = T6.""id"") ORDER BY ""testmodel_d"".""c_ptr_id"" ASC'
}}}

I had a look at the model_inheritance tests, and couldn't see any that were testing to the depth I'm doing there, so either I'm doing something wrong, SQlite is (as always) being a pain, or the tests may not go far enough."	Bug	closed	Database layer (models, ORM)	1.5	Normal	fixed			Unreviewed	0	0	0	0	0	0