Create a signal to unassign roles from user when deleted

Add a signal to the api app that automatically unassigns
deleted roles from users that have them

3 files changed, 22 insertions, 1 deletions

diff --git a/pydis_site/apps/api/__init__.py b/pydis_site/apps/api/__init__.py
index e69de29b..afa5b4d5 100644
--- a/pydis_site/apps/api/__init__.py
+++ b/pydis_site/apps/api/__init__.py
@@ -0,0 +1 @@
+default_app_config = 'pydis_site.apps.api.apps.ApiConfig'
diff --git a/pydis_site/apps/api/apps.py b/pydis_site/apps/api/apps.py
index 76810b2e..18eda9e3 100644
--- a/pydis_site/apps/api/apps.py
+++ b/pydis_site/apps/api/apps.py
@@ -4,4 +4,12 @@ from django.apps import AppConfig
 class ApiConfig(AppConfig):
     """Django AppConfig for the API app."""
 
-    name = 'api'
+    name = 'pydis_site.apps.api'
+
+    def ready(self) -> None:
+        """
+        Gets called as soon as the registry is fully populated.
+
+        https://docs.djangoproject.com/en/3.2/ref/applications/#django.apps.AppConfig.ready
+        """
+        import pydis_site.apps.api.signals  # noqa: F401
diff --git a/pydis_site/apps/api/signals.py b/pydis_site/apps/api/signals.py
new file mode 100644
index 00000000..c69704b1
--- /dev/null
+++ b/pydis_site/apps/api/signals.py
@@ -0,0 +1,12 @@
+from django.db.models.signals import pre_delete
+from django.dispatch import receiver
+
+from pydis_site.apps.api.models.bot import Role, User
+
+
+@receiver(signal=pre_delete, sender=Role)
+def delete_role_from_user(sender: Role, instance: Role, **kwargs) -> None:
+    """Unassigns the Role (instance) that is being deleted from every user that has it."""
+    for user in User.objects.filter(roles__contains=[instance.id]):
+        del user.roles[user.roles.index(instance.id)]
+        user.save()