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
14930	`values_list()` fails on queryset ordered by extra column	Luc Saffre	fhahn	"`values_list()` returns an uncomplete QuerySet when called on a 
QuerySet that is ordered by a column defined using `QuerySet.extra()`.

For example, the following QuerySet works as expected::

{{{
  qs = Article.objects.extra(select={'id_plus_one': 'id+1'},order_by=['id_plus_one'])
}}}
  
but when I execute a `values_list('id')` on this, I'll get a 
`FieldError: Cannot resolve keyword 'id_plus_one' into field`.

To show this problem, I added 
a test case to `django/tests/modeltests/lookup/tests.py`:

{{{
  # See http://lino.saffre-rumma.net/tickets/19.html
  qs = Article.objects.extra(select={'id_plus_one': 'id+1'}).order_by('id_plus_one')
  print qs.query.extra_select # output: {'id_plus_one': (u'id+1', [])}
  self.assertQuerysetEqual(qs,
    [
      self.a1,
      self.a2,
      self.a3,
      self.a4,
      self.a5,
      self.a6,
      self.a7
    ],
    transform=identity)
  qs = qs.values_list('id')
  print qs.query.extra_select # output: {}
  self.assertQuerysetEqual(
      qs,
      [
          [self.a1.id],
          [self.a2.id],
          [self.a3.id],
          [self.a4.id],
          [self.a5.id],
          [self.a6.id],
          [self.a7.id]
      ],
      transform=identity)
}}}
            
[http://code.google.com/p/lino/source/browse/patches/20101221.diff Here] is a diff file for this code against Django 14995.

Running the lookup tests with this patch will say::


{{{
  ERROR: test_values_list (modeltests.lookup.tests.LookupTests)
  ----------------------------------------------------------------------
  Traceback (most recent call last):
    File ""L:\snapshots\django\tests\modeltests\lookup\tests.py"", line 347, in test_values_list
      transform=identity)
    File ""l:\snapshots\django\django\test\testcases.py"", line 526, in assertQuerysetEqual
      return self.assertEqual(map(transform, qs), values)
    File ""l:\snapshots\django\django\db\models\query.py"", line 84, in __len__
      self._result_cache.extend(list(self._iter))
    File ""l:\snapshots\django\django\db\models\query.py"", line 953, in iterator
      for row in self.query.get_compiler(self.db).results_iter():
    File ""l:\snapshots\django\django\db\models\sql\compiler.py"", line 680, in results_iter
      for rows in self.execute_sql(MULTI):
    File ""l:\snapshots\django\django\db\models\sql\compiler.py"", line 725, in execute_sql
      sql, params = self.as_sql()
    File ""l:\snapshots\django\django\db\models\sql\compiler.py"", line 60, in as_sql
      ordering, ordering_group_by = self.get_ordering()
    File ""l:\snapshots\django\django\db\models\sql\compiler.py"", line 349, in get_ordering
      self.query.model._meta, default_order=asc):
    File ""l:\snapshots\django\django\db\models\sql\compiler.py"", line 378, in find_ordering_name
      opts, alias, False)
    File ""l:\snapshots\django\django\db\models\sql\query.py"", line 1215, in setup_joins
      ""Choices are: %s"" % (name, "", "".join(names)))
  FieldError: Cannot resolve keyword 'id_plus_one' into field. Choices are: author, headline, id, pub_date, tag

}}}

AFAICS `qs.query.extra_select` on the `ValuesListQuerySet` should *not* be empty.
"	Bug	closed	Database layer (models, ORM)	dev	Normal	fixed		robinchew@… simon@… gosia lau@… Ludovic Delaveau django@… fhahn timograham@…	Ready for checkin	1	0	0	0	1	0