Ticket #9797: annotate-count.diff

django/db/models/sql/query.py

@@ -277 +277 @@
         """
         Performs a COUNT() query using the current filter constraints.
         """
-        from subqueries import CountQuery
+        from django.db.models import Count as AggCount
         obj = self.clone()
-        obj.clear_ordering(True)
         obj.clear_limits()
+        obj.clear_ordering(True)
         obj.select_related = False
         obj.related_select_cols = []
         obj.related_select_fields = []
-        if len(obj.select) > 1:
-            obj = self.clone(CountQuery, _query=obj, where=self.where_class(),
-                    distinct=False)
-            obj.select = []
-            obj.aggregate_select = {}
-            obj.extra_select = {}
-        obj.add_count_column()
-        data = obj.execute_sql(SINGLE)
-        if not data:
-            return 0
-        number = data[0]
-
+        obj.add_aggregate(AggCount('pk', distinct=obj.distinct), self.model, 'f', True)
+        number = obj.get_aggregation()['f']
+        
         # Apply offset and limit constraints manually, since using LIMIT/OFFSET
         # in SQL (in variants that provide them) doesn't change the COUNT
         # output.

tests/regressiontests/aggregation_regress/models.py

@@ -121 +121 @@
 ...
 FieldError: Cannot resolve keyword 'foo' into field. Choices are: authors, id, isbn, name, pages, price, publisher, store, num_authors
 
+>>> Book.objects.annotate(num_authors=Count('authors')).count()
+6
+
 """
 }