fix grouped data when there is no drilldown chosen (fixes #12718)

bijoe/views.py

@@ -137,6 +137,8 @@ class CubeMixin(object):
     def get_grouped_data(self, cleaned_data, stringify=True):
         data = self.get_data(cleaned_data, stringify=stringify)
         dims = len(cleaned_data.get('drilldown', []))
+        if not dims:
+            return ([(v, 0) for v in row] for row in data)
         grouped = OrderedDict()
         for row in data:
             d = grouped