Ticket #12822: ticket_12822_tests_with_fix.diff

django/db/models/sql/query.py

@@ -240 +240 @@
             obj.aggregate_select_mask = None
         else:
             obj.aggregate_select_mask = self.aggregate_select_mask.copy()
-        if self._aggregate_select_cache is None:
-            obj._aggregate_select_cache = None
-        else:
-            obj._aggregate_select_cache = self._aggregate_select_cache.copy()
+        # _aggregate_select_cache cannot be copied, as doing so breaks the
+        # (necessary) state in which both aggregates and
+        # _aggregate_select_cache point to the same underlying objects.
+        # It will get re-populated in the cloned queryset the next time it's
+        # used.
+        obj._aggregate_select_cache = None
         obj.max_depth = self.max_depth
         obj.extra = self.extra.copy()
         if self.extra_select_mask is None:

new file tests/regressiontests/aggregation_regress/tests.py

@@ +1 @@
+from django.test import TestCase
+from django.db.models import Max
+
+from regressiontests.aggregation_regress.models import *
+
+
+class AggregationTests(TestCase):
+
+    def test_aggregates_in_where_clause(self):
+        """
+        Regression test for #12822: DatabaseError: aggregates not allowed in
+        WHERE clause
+
+        Tests that the subselect works and returns results equivalent to a
+        query with the IDs listed.
+        
+        Before the corresponding fix for this bug, this test passed in 1.1 and
+        failed in 1.2-beta (trunk).
+        """
+        qs = Book.objects.values('contact').annotate(Max('id'))
+        qs = qs.order_by('contact').values_list('id__max', flat=True)
+        # don't do anything with the queryset (qs) before including it as a
+        # subquery
+        books = Book.objects.order_by('id')
+        qs1 = books.filter(id__in=qs)
+        qs2 = books.filter(id__in=list(qs))
+        self.assertEqual(list(qs1), list(qs2))
+
+    def test_aggregates_in_where_clause_pre_eval(self):
+        """
+        Regression test for #12822: DatabaseError: aggregates not allowed in
+        WHERE clause
+
+        Same as the above test, but evaluates the queryset for the subquery
+        before it's used as a subquery.
+        
+        Before the corresponding fix for this bug, this test failed in both
+        1.1 and 1.2-beta (trunk).
+        """
+        qs = Book.objects.values('contact').annotate(Max('id'))
+        qs = qs.order_by('contact').values_list('id__max', flat=True)
+        # force the queryset (qs) for the subquery to be evaluated in its
+        # current state
+        list(qs)
+        books = Book.objects.order_by('id')
+        qs1 = books.filter(id__in=qs)
+        qs2 = books.filter(id__in=list(qs))
+        self.assertEqual(list(qs1), list(qs2))