UPD: added app to submit participant registrations.

dav_registration/utils.py

@@ -0,0 +1,13 @@
+import logging
+from django.utils import timezone
+
+from .models import Registration
+
+logger = logging.getLogger(__name__)
+
+
+def purge_registrations():
+    now = timezone.now()
+    for r in Registration.objects.filter(purge_at__lte=now):
+        logger.info('Purge registration \'%s\'', r)
+        r.delete()