fix count for query with group by and no agg

sqlagg/base.py

@@ -111,7 +111,7 @@ def count(self, connection, filter_values):
         query = self._build_query_generic(self.columns, group_by=self.group_by, filters=self.filters,
                                           distinct_on=self.distinct_on)
 
-        if any(col.aggregate_fn for col in self.columns):
+        if self.group_by or any(col.aggregate_fn for col in self.columns):
             query = sqlalchemy.select([sqlalchemy.func.count()]).select_from(query.alias())
         else:
             query = query.with_only_columns([sqlalchemy.func.count()]).order_by(None)

tests/tests.py

@@ -265,6 +265,22 @@ def test_count_no_grouping(self):
         vc.append_column(SimpleColumn('indicator_a'))
         self.assertEqual(2, vc.count(self.session.connection(), {'username': 'user1'},))
 
+    def test_count_group_no_agg(self):
+        # due to past idiosyncrasy of sqlagg CommCare was adding a group by on
+        # primary keys as follows:
+        #
+        #   SELECT username_ea02198f AS column_0, doc_id AS doc_id FROM ucr_table_x GROUP BY doc_id
+        #
+        # When doing a count of this query we have to do a subquery
+
+        vc = QueryContext(
+            "user_table",
+            group_by=['indicator_a']
+        )
+
+        vc.append_column(SimpleColumn('indicator_a'))
+        self.assertEqual(4, vc.count(self.session.connection(),))
+
     def test_count_with_nulls(self):
         vc = QueryContext(
             "user_table",