Chore/fix: cleanup user or group references in settings upon deletion (#10049)

src/documents/signals/handlers.py

@@ -13,6 +13,7 @@ from celery.signals import task_failure
 from celery.signals import task_postrun
 from celery.signals import task_prerun
 from django.conf import settings
+from django.contrib.auth.models import Group
 from django.contrib.auth.models import User
 from django.db import DatabaseError
 from django.db import close_old_connections
@@ -38,6 +39,7 @@ from documents.models import MatchingModel
 from documents.models import PaperlessTask
 from documents.models import SavedView
 from documents.models import Tag
+from documents.models import UiSettings
 from documents.models import Workflow
 from documents.models import WorkflowAction
 from documents.models import WorkflowRun
@@ -581,6 +583,51 @@ def cleanup_custom_field_deletion(sender, instance: CustomField, **kwargs):
         )
 
 
+@receiver(models.signals.post_delete, sender=User)
+@receiver(models.signals.post_delete, sender=Group)
+def cleanup_user_deletion(sender, instance: User | Group, **kwargs):
+    """
+    When a user or group is deleted, remove non-cascading references.
+    At the moment, just the default permission settings in UiSettings.
+    """
+    # Remove the user permission settings e.g.
+    #   DEFAULT_PERMS_OWNER: 'general-settings:permissions:default-owner',
+    #   DEFAULT_PERMS_VIEW_USERS: 'general-settings:permissions:default-view-users',
+    #   DEFAULT_PERMS_VIEW_GROUPS: 'general-settings:permissions:default-view-groups',
+    #   DEFAULT_PERMS_EDIT_USERS: 'general-settings:permissions:default-edit-users',
+    #   DEFAULT_PERMS_EDIT_GROUPS: 'general-settings:permissions:default-edit-groups',
+    for ui_settings in UiSettings.objects.all():
+        try:
+            permissions = ui_settings.settings.get("permissions", {})
+            updated = False
+            if isinstance(instance, User):
+                if permissions.get("default_owner") == instance.pk:
+                    permissions["default_owner"] = None
+                    updated = True
+                if instance.pk in permissions.get("default_view_users", []):
+                    permissions["default_view_users"].remove(instance.pk)
+                    updated = True
+                if instance.pk in permissions.get("default_change_users", []):
+                    permissions["default_change_users"].remove(instance.pk)
+                    updated = True
+            elif isinstance(instance, Group):
+                if instance.pk in permissions.get("default_view_groups", []):
+                    permissions["default_view_groups"].remove(instance.pk)
+                    updated = True
+                if instance.pk in permissions.get("default_change_groups", []):
+                    permissions["default_change_groups"].remove(instance.pk)
+                    updated = True
+            if updated:
+                ui_settings.settings["permissions"] = permissions
+                ui_settings.save(update_fields=["settings"])
+        except Exception as e:
+            logger.error(
+                f"Error while cleaning up user {instance.pk} ({instance.username}) from ui_settings: {e}"
+                if isinstance(instance, User)
+                else f"Error while cleaning up group {instance.pk} ({instance.name}) from ui_settings: {e}",
+            )
+
+
 def add_to_index(sender, document, **kwargs):
     from documents import index
 

src/paperless/tests/test_signals.py

@@ -6,6 +6,7 @@ from django.http import HttpRequest
 from django.test import TestCase
 from django.test import override_settings
 
+from documents.models import UiSettings
 from paperless.signals import handle_failed_login
 from paperless.signals import handle_social_account_updated
 
@@ -190,3 +191,76 @@ class TestSyncSocialLoginGroups(TestCase):
             sociallogin=sociallogin,
         )
         self.assertEqual(list(user.groups.all()), [])
+
+
+class TestUserGroupDeletionCleanup(TestCase):
+    """
+    Test that when a user or group is deleted, references are cleaned up properly
+    from ui_settings
+    """
+
+    def test_user_group_deletion_cleanup(self):
+        """
+        GIVEN:
+            - Existing user
+            - Existing group
+        WHEN:
+            - The user is deleted
+            - The group is deleted
+        THEN:
+            - References in ui_settings are cleaned up
+        """
+        user = User.objects.create_user(username="testuser")
+        user2 = User.objects.create_user(username="testuser2")
+        group = Group.objects.create(name="testgroup")
+
+        ui_settings = UiSettings.objects.create(
+            user=user,
+            settings={
+                "permissions": {
+                    "default_owner": user2.id,
+                    "default_view_users": [user2.id],
+                    "default_change_users": [user2.id],
+                    "default_view_groups": [group.id],
+                    "default_change_groups": [group.id],
+                },
+            },
+        )
+
+        user2.delete()
+        ui_settings.refresh_from_db()
+        permissions = ui_settings.settings.get("permissions", {})
+        self.assertIsNone(permissions.get("default_owner"))
+        self.assertEqual(permissions.get("default_view_users"), [])
+        self.assertEqual(permissions.get("default_change_users"), [])
+
+        group.delete()
+        ui_settings.refresh_from_db()
+        permissions = ui_settings.settings.get("permissions", {})
+        self.assertEqual(permissions.get("default_view_groups"), [])
+        self.assertEqual(permissions.get("default_change_groups"), [])
+
+    def test_user_group_deletion_error_handling(self):
+        """
+        GIVEN:
+            - Existing user and group
+        WHEN:
+            - The user is deleted and an error occurs during the signal handling
+        THEN:
+            - Error is logged and the system remains stable
+        """
+        user = User.objects.create_user(username="testuser")
+        user2 = User.objects.create_user(username="testuser2")
+        user2_id = user2.id
+        Group.objects.create(name="testgroup")
+
+        UiSettings.objects.create(
+            user=user,
+        )  # invalid, no settings, this probably should not happen in production
+
+        with self.assertLogs("paperless.handlers", level="ERROR") as cm:
+            user2.delete()
+            self.assertIn(
+                f"Error while cleaning up user {user2_id}",
+                cm.output[0],
+            )