Fixed #31097 -- Fixed crash of ArrayAgg and StringAgg with filter when used in Subquery.

AUTHORS

@@ -242,6 +242,7 @@ answer newbie questions, and generally made Django that much better:
     David Sanders <dsanders11@ucsbalum.com>
     David Schein
     David Tulig <david.tulig@gmail.com>
+    David Wobrock <david.wobrock@gmail.com>
     Davide Ceretti <dav.ceretti@gmail.com>
     Deepak Thukral <deep.thukral@gmail.com>
     Denis Kuzmichyov <kuzmichyov@gmail.com>

django/contrib/postgres/aggregates/mixins.py

@@ -40,16 +40,7 @@ class OrderableAggMixin:
         return super().set_source_expressions(exprs[:self._get_ordering_expressions_index()])
 
     def get_source_expressions(self):
-        return self.source_expressions + self.ordering
-
-    def get_source_fields(self):
-        # Filter out fields contributed by the ordering expressions as
-        # these should not be used to determine which the return type of the
-        # expression.
-        return [
-            e._output_field_or_none
-            for e in self.get_source_expressions()[:self._get_ordering_expressions_index()]
-        ]
+        return super().get_source_expressions() + self.ordering
 
     def _get_ordering_expressions_index(self):
         """Return the index at which the ordering expressions start."""

tests/postgres_tests/test_aggregates.py

@@ -21,7 +21,7 @@ except ImportError:
 class TestGeneralAggregate(PostgreSQLTestCase):
     @classmethod
     def setUpTestData(cls):
-        AggregateTestModel.objects.create(boolean_field=True, char_field='Foo1', integer_field=0)
+        cls.agg1 = AggregateTestModel.objects.create(boolean_field=True, char_field='Foo1', integer_field=0)
         AggregateTestModel.objects.create(boolean_field=False, char_field='Foo2', integer_field=1)
         AggregateTestModel.objects.create(boolean_field=False, char_field='Foo4', integer_field=2)
         AggregateTestModel.objects.create(boolean_field=True, char_field='Foo3', integer_field=0)
@@ -249,6 +249,50 @@ class TestGeneralAggregate(PostgreSQLTestCase):
                 ).order_by('char_field').values_list('char_field', 'agg')
                 self.assertEqual(list(values), expected_result)
 
+    def test_string_agg_array_agg_filter_in_subquery(self):
+        StatTestModel.objects.bulk_create([
+            StatTestModel(related_field=self.agg1, int1=0, int2=5),
+            StatTestModel(related_field=self.agg1, int1=1, int2=4),
+            StatTestModel(related_field=self.agg1, int1=2, int2=3),
+        ])
+        for aggregate, expected_result in (
+            (
+                ArrayAgg('stattestmodel__int1', filter=Q(stattestmodel__int2__gt=3)),
+                [('Foo1', [0, 1]), ('Foo2', None)],
+            ),
+            (
+                StringAgg(
+                    Cast('stattestmodel__int2', CharField()),
+                    delimiter=';',
+                    filter=Q(stattestmodel__int1__lt=2),
+                ),
+                [('Foo1', '5;4'), ('Foo2', None)],
+            ),
+        ):
+            with self.subTest(aggregate=aggregate.__class__.__name__):
+                subquery = AggregateTestModel.objects.filter(
+                    pk=OuterRef('pk'),
+                ).annotate(agg=aggregate).values('agg')
+                values = AggregateTestModel.objects.annotate(
+                    agg=Subquery(subquery),
+                ).filter(
+                    char_field__in=['Foo1', 'Foo2'],
+                ).order_by('char_field').values_list('char_field', 'agg')
+                self.assertEqual(list(values), expected_result)
+
+    def test_string_agg_filter_in_subquery_with_exclude(self):
+        subquery = AggregateTestModel.objects.annotate(
+            stringagg=StringAgg(
+                'char_field',
+                delimiter=';',
+                filter=Q(char_field__endswith='1'),
+            )
+        ).exclude(stringagg='').values('id')
+        self.assertSequenceEqual(
+            AggregateTestModel.objects.filter(id__in=Subquery(subquery)),
+            [self.agg1],
+        )
+
 
 class TestAggregateDistinct(PostgreSQLTestCase):
     @classmethod