Fixed #8819 -- Don't include two copies of extra-select columns in the query.

This was triggered by r8794, but was, in fact, fairly fragile before then. The
current fix is the correct way we should be doing this.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8898 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/sql/query.py

@@ -630,7 +630,7 @@ class Query(object):
             else:
                 col, order = get_order_dir(field, asc)
                 elt = qn2(col)
-                if distinct and elt not in select_aliases:
+                if distinct and col not in select_aliases:
                     ordering_aliases.append(elt)
                 result.append('%s %s' % (elt, order))
         self.ordering_aliases = ordering_aliases

tests/regressiontests/extra_regress/models.py

@@ -98,4 +98,13 @@ True
 >>> Order.objects.extra(where=["username=%s"], params=["fred"], tables=["auth_user"]).order_by('created_by')
 []
 
+# Regression test for #8819: Fields in the extra(select=...) list should be
+# available to extra(order_by=...).
+>>> User.objects.extra(select={'extra_field': 1}).distinct()
+[<User: fred>]
+>>> User.objects.extra(select={'extra_field': 1}, order_by=['extra_field'])
+[<User: fred>]
+>>> User.objects.extra(select={'extra_field': 1}, order_by=['extra_field']).distinct()
+[<User: fred>]
+
 """}