Allow an alias to be used for the extra param

generic_aggregation/tests/settings.py

@@ -1,6 +1,6 @@
 DATABASE_ENGINE = 'sqlite3'
-DATABASE_ENGINE = 'postgresql_psycopg2'
-DATABASE_NAME = 'test_main'
+#DATABASE_ENGINE = 'postgresql_psycopg2'
+#DATABASE_NAME = 'test_main'
 
 INSTALLED_APPS = [
     'django.contrib.contenttypes',

generic_aggregation/tests/tests.py

@@ -121,3 +121,17 @@ def test_charfield_pks(self):
 
         aggregated = generic_aggregate(Food.objects.all(), CharFieldGFK.content_object, 'name', models.Count)
         self.assertEqual(aggregated, 3)
+
+    def test_custom_alias(self):
+        annotated_qs = generic_annotate(Food.objects.all(), Rating.content_object, 'rating', models.Count, alias='count')
+        food_a, food_b = annotated_qs
+
+        self.assertEqual(food_a.count, 4)
+        self.assertEqual(food_a.name, 'apple')
+
+    def test_ascending_order(self):
+        annotated_qs = generic_annotate(Food.objects.all(), Rating.content_object, 'rating', models.Count, desc=False, alias='count')
+        food_a, food_b = annotated_qs
+
+        self.assertEqual(food_b.count, 4)
+        self.assertEqual(food_b.name, 'apple')

generic_aggregation/utils.py

@@ -34,8 +34,8 @@ def gfk_expression(qs_model, gfk_field):
 
 
 def generic_annotate(queryset, gfk_field, aggregate_field, aggregator=models.Sum,
-        generic_queryset=None, desc=True):
-    ordering = desc and '-score' or 'score'
+        generic_queryset=None, desc=True, alias='score'):
+    ordering = desc and '-%s' % alias or alias
     content_type = ContentType.objects.get_for_model(queryset.model)
 
     qn = connection.ops.quote_name
@@ -76,7 +76,7 @@ def generic_annotate(queryset, gfk_field, aggregate_field, aggregator=models.Sum
         inner_query_params = []
 
     queryset = queryset.extra(
-        select={'score': extra},
+        select={alias: extra},
         select_params=inner_query_params,
         order_by=[ordering]
     )