create profile if none exists when trying to save User

tom_common/signals.py

@@ -1,4 +1,4 @@
-from django.db.models.signals import post_save, pre_delete
+from django.db.models.signals import post_save
 from django.contrib.auth.models import User
 from django.dispatch import receiver
 from tom_common.models import Profile
@@ -14,4 +14,9 @@ def create_profile(sender, instance, created, **kwargs):
 @receiver(post_save, sender=User)
 def save_profile(sender, instance, **kwargs):
     """When a user is saved, save their profile."""
-    instance.profile.save()
+    # Take advantage of the fact that logging in updates a user's last_login field
+    # to create a profile for users that don't have one.
+    try:
+        instance.profile.save()
+    except User.profile.RelatedObjectDoesNotExist:
+        Profile.objects.create(user=instance)