1 files changed, 8 insertions, 1 deletions
diff --git a/models.py b/models.py
index 15f378a..c122bfd 100644
--- a/models.py
+++ b/models.py
@@ -16,7 +16,7 @@
 from functools import reduce
 
 from django.db import models
-from django.db.models import Manager, Q
+from django.db.models import Count, Manager, OuterRef, Q, Subquery
 from django.db.models.functions import ExtractWeek, ExtractYear
 from django.utils import timezone
 from django.utils.text import slugify
@@ -104,6 +104,13 @@ class GroupManager(Manager):
                                           mention=group.mention,
                                           source=group.source)
 
+    def get_relevant_groups(self, start, **criteria):
+        courses = Course.objects.filter(groups=OuterRef("pk"), begin__gte=start) \
+                                .only("pk")[:1]
+        return self.get_queryset().annotate(c=Subquery(courses,
+                                                       output_field=models.IntegerField())) \
+                                  .filter(c__isnull=False, **criteria).order_by("name")
+
 
 class Group(SlugModel):
     objects = GroupManager()