1 files changed, 6 insertions, 4 deletions
diff --git a/models.py b/models.py
index b9f1ba7..a90e9da 100644
--- a/models.py
+++ b/models.py
@@ -72,10 +72,12 @@ class Timetable(SlugModel):
 
 class GroupManager(Manager):
     def get_parents(self, group):
-        groups_criteria = Q(subgroup="") | Q(subgroup__startswith=group.subgroup) | \
-                          reduce(lambda x, y: x | y,
-                                 [Q(subgroup=group.subgroup[:i])
-                                  for i in range(1, len(group.subgroup) + 1)])
+        groups_criteria = Q(subgroup="") | Q(subgroup__startswith=group.subgroup)
+
+        if len(group.subgroup) != 0:
+            groups_criteria |= reduce(lambda x, y: x | y,
+                                      [Q(subgroup=group.subgroup[:i])
+                                       for i in range(1, len(group.subgroup + 1))])
 
         return self.get_queryset().filter(groups_criteria, mention=group.mention,
                                           timetable=group.timetable)