Support for handling non-integer gfk fk_fields, like Comments.

generic_aggregation/tests/models.py

@@ -20,3 +20,10 @@ class Rating(models.Model):
 
     def __unicode__(self):
         return '%s rated %s' % (self.content_object, self.rating)
+
+
+class CharFieldGFK(models.Model):
+    name = models.CharField(max_length=255)
+    object_id = models.CharField(max_length=10)
+    content_type = models.ForeignKey(ContentType)
+    content_object = GenericForeignKey(ct_field='content_type', fk_field='object_id')

generic_aggregation/tests/tests.py

@@ -5,7 +5,7 @@
 from django.test import TestCase
 
 from generic_aggregation import generic_annotate, generic_aggregate
-from generic_aggregation.tests.models import Food, Rating
+from generic_aggregation.tests.models import Food, Rating, CharFieldGFK
 
 class SimpleTest(TestCase):
     def setUp(self):
@@ -102,3 +102,22 @@ def test_subset_aggregation(self):
 
         aggregated = generic_aggregate(Food.objects.all(), Rating.content_object, 'rating', models.Count, todays_ratings)
         self.assertEqual(aggregated, 4)
+
+    def test_charfield_pks(self):
+        a1 = CharFieldGFK.objects.create(name='a1', content_object=self.apple)
+        a2 = CharFieldGFK.objects.create(name='a2', content_object=self.apple)
+        o1 = CharFieldGFK.objects.create(name='o1', content_object=self.orange)
+
+        annotated_qs = generic_annotate(Food.objects.all(), CharFieldGFK.content_object, 'name', models.Count)
+        self.assertEqual(annotated_qs.count(), 2)
+
+        food_a, food_b = annotated_qs
+
+        self.assertEqual(food_b.score, 1)
+        self.assertEqual(food_b.name, 'orange')
+
+        self.assertEqual(food_a.score, 2)
+        self.assertEqual(food_a.name, 'apple')
+
+        aggregated = generic_aggregate(Food.objects.all(), CharFieldGFK.content_object, 'name', models.Count)
+        self.assertEqual(aggregated, 3)

generic_aggregation/utils.py

@@ -14,6 +14,25 @@ def query_as_nested_sql(query):
     else:
         return query.get_compiler(connection=connection).as_nested_sql()
 
+def gfk_expression(qs_model, gfk_field):
+    # handle casting the GFK field if need be
+    qn = connection.ops.quote_name
+
+    pk_field_type = qs_model._meta.pk.db_type()
+    gfk_field_type = gfk_field.model._meta.get_field(gfk_field.fk_field).db_type()
+
+    if pk_field_type == 'serial':
+        pk_field_type = 'integer'
+
+    if pk_field_type != gfk_field_type:
+        # cast the gfk to the pk type
+        gfk_expr = "CAST(%s AS %s)" % (qn(gfk_field.fk_field), pk_field_type)
+    else:
+        gfk_expr = qn(gfk_field.fk_field) # the object_id field on the GFK
+
+    return gfk_expr
+
+
 def generic_annotate(queryset, gfk_field, aggregate_field, aggregator=models.Sum,
         generic_queryset=None, desc=True):
     ordering = desc and '-score' or 'score'
@@ -28,18 +47,19 @@ def generic_annotate(queryset, gfk_field, aggregate_field, aggregator=models.Sum
         qn(gfk_field.model._meta.db_table), # table holding gfk'd item info
         qn(gfk_field.ct_field + '_id'), # the content_type field on the GFK
         content_type.pk, # the content_type id we need to match
-        qn(gfk_field.fk_field), # the object_id field on the GFK
+        gfk_expression(queryset.model, gfk_field),
         qn(queryset.model._meta.db_table), # the table and pk from the main
         qn(queryset.model._meta.pk.name)   # part of the query
     )
 
-    extra = """
+    sql_template = """
         SELECT %s(%s) AS aggregate_score
         FROM %s
         WHERE
             %s=%s AND
-            %s=%s.%s
-    """ % params
+            %s=%s.%s"""
+
+    extra = sql_template % params
 
     if generic_queryset is not None:
         generic_query = generic_queryset.values_list('pk').query
@@ -80,7 +100,7 @@ def generic_aggregate(queryset, gfk_field, aggregate_field, aggregator=models.Su
         qn(gfk_field.model._meta.db_table), # table holding gfk'd item info
         qn(gfk_field.ct_field + '_id'), # the content_type field on the GFK
         content_type.pk, # the content_type id we need to match
-        qn(gfk_field.fk_field), # the object_id field on the GFK
+        gfk_expression(queryset.model, gfk_field), # the object_id field on the GFK
     )
 
     query_start = """