Fixed #10089 -- Corrected handling of aggregates when the query set contains no items (and the cursor returns None). Thanks to Kyle Fox for the report, and david for the initial patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9786 bcc190cf-cafb-0310-a4f2-bffc1f526a37

2 files changed, 18 insertions, 0 deletions

diff --git a/tests/regressiontests/aggregation_regress/fixtures/initial_data.json b/tests/regressiontests/aggregation_regress/fixtures/initial_data.json
index a632c4077a..7c5d62c2c6 100644
--- a/tests/regressiontests/aggregation_regress/fixtures/initial_data.json
+++ b/tests/regressiontests/aggregation_regress/fixtures/initial_data.json
@@ -32,6 +32,14 @@
         }
     },
     {
+        "pk": 5,
+        "model": "aggregation_regress.publisher",
+        "fields": {
+            "name": "Jonno's House of Books",
+            "num_awards": 0
+        }
+    },
+    {
         "pk": 1,
         "model": "aggregation_regress.book",
         "fields": {
diff --git a/tests/regressiontests/aggregation_regress/models.py b/tests/regressiontests/aggregation_regress/models.py
index 8a590dca8b..7ff54b2c0d 100644
--- a/tests/regressiontests/aggregation_regress/models.py
+++ b/tests/regressiontests/aggregation_regress/models.py
@@ -164,6 +164,16 @@ FieldError: Cannot resolve keyword 'foo' into field. Choices are: authors, id, i
 >>> len(Book.objects.annotate(num_authors=Count('authors')).exclude(num_authors__lt=2).filter(num_authors__lt=3))
 2
 
+# Regression for #10089: Check handling of empty result sets with aggregates
+>>> Book.objects.filter(id__in=[]).count()
+0
+
+>>> Book.objects.filter(id__in=[]).aggregate(num_authors=Count('authors'), avg_authors=Avg('authors'), max_authors=Max('authors'), max_price=Max('price'), max_rating=Max('rating'))
+{'max_authors': None, 'max_rating': None, 'num_authors': 0, 'avg_authors': None, 'max_price': None}
+
+>>> Publisher.objects.filter(pk=5).annotate(num_authors=Count('book__authors'), avg_authors=Avg('book__authors'), max_authors=Max('book__authors'), max_price=Max('book__price'), max_rating=Max('book__rating')).values()
+[{'max_authors': None, 'name': u"Jonno's House of Books", 'num_awards': 0, 'max_price': None, 'num_authors': 0, 'max_rating': None, 'id': 5, 'avg_authors': None}]
+
 """
 }