diff --git a/django/db/models/query.py b/django/db/models/query.py index 9c3aeaa8d3..6a6a82968f 100644 --- a/django/db/models/query.py +++ b/django/db/models/query.py @@ -1132,6 +1132,14 @@ class EmptyQuerySet(QuerySet): """ return 0 + def aggregate(self, *args, **kwargs): + """ + Return a dict mapping the aggregate names to None + """ + for arg in args: + kwargs[arg.default_alias] = arg + return dict([(key, None) for key in kwargs]) + # EmptyQuerySet is always an empty result in where-clauses (and similar # situations). value_annotation = False diff --git a/tests/regressiontests/aggregation_regress/tests.py b/tests/regressiontests/aggregation_regress/tests.py index 15692b6422..49e1e611e9 100644 --- a/tests/regressiontests/aggregation_regress/tests.py +++ b/tests/regressiontests/aggregation_regress/tests.py @@ -662,6 +662,13 @@ class AggregationTests(TestCase): {"pk__count": None} ) + def test_none_call_before_aggregate(self): + # Regression for #11789 + self.assertEqual( + Author.objects.none().aggregate(Avg('age')), + {'age__avg': None} + ) + def test_annotate_and_join(self): self.assertEqual( Author.objects.annotate(c=Count("friends__name")).exclude(friends__name="Joe").count(),