teams/models.py

@@ -1,7 +1,7 @@
 import logging
 
 from django.contrib.auth import get_user_model
-from django.db import models
+from django.db import models, transaction
 from django.urls import reverse
 
 from common.model_mixins import CreatedModifiedMixin
@@ -49,3 +49,22 @@ class TeamsUsers(CreatedModifiedMixin, models.Model):
     @property
     def is_manager(self) -> bool:
         return self.role == TEAM_ROLE_MANAGER
+
+    @transaction.atomic
+    def delete(self):
+        # erase extension.team field if the user was the last maintainer from the team
+        for extension in self.user.extensions.filter(team=self.team).all():
+            # assuming small datasets, not optimizing db access
+            authors = extension.authors.all()
+            has_other_authors_from_the_team = False
+            for author in authors:
+                if author == self.user:
+                    continue
+                if self.team in author.teams.all():
+                    has_other_authors_from_the_team = True
+                    break
+            if not has_other_authors_from_the_team:
+                extension.team = None
+                extension.save(update_fields={'team'})
+
+        return super().delete()