UN-3375 [FIX] Support multiple nullable FK paths in OrganizationFilterBackend (#1889)

Add org_filter_paths ViewSet attribute for models with multiple nullable
FK paths to Organization (e.g. Notification → Pipeline or API → Workflow
→ Organization). When set, the filter uses OR across all paths instead
of BFS which only finds one path and misses records linked via the other.

Apply org_filter_paths to NotificationViewSet to fix 404 on notification
PUT/DELETE operations.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: muhammad-ali-e

backend/notification_v2/views.py

@@ -13,6 +13,10 @@
 
 class NotificationViewSet(viewsets.ModelViewSet):
     serializer_class = NotificationSerializer
+    org_filter_paths = [
+        "pipeline__workflow__organization",
+        "api__workflow__organization",
+    ]
 
     def get_queryset(self):
         queryset = Notification.objects.all()

backend/utils/filters/organization_filter.py

@@ -1,12 +1,18 @@
 import logging
 
+from django.db.models import Q
 from rest_framework.filters import BaseFilterBackend
 
 from utils.models.org_path_discovery import get_org_path
 from utils.user_context import UserContext
 
 logger = logging.getLogger(__name__)
 
+# ViewSet attributes read by OrganizationFilterBackend.
+# Use these constants when setting attributes on ViewSets to avoid typos.
+SKIP_ORG_FILTER = "skip_org_filter"
+ORG_FILTER_PATHS = "org_filter_paths"
+
 
 class OrganizationFilterBackend(BaseFilterBackend):
     """Global filter backend that enforces organization scoping.
@@ -24,10 +30,20 @@ class OrganizationFilterBackend(BaseFilterBackend):
     rather than replacing it.
 
     Opt-out: set skip_org_filter = True on the viewset.
+
+    For models with multiple nullable FK paths to Organization, set
+    org_filter_paths on the viewset to use OR filtering across all
+    paths (skips BFS):
+
+        class NotificationViewSet(viewsets.ModelViewSet):
+            org_filter_paths = [
+                "pipeline__workflow__organization",
+                "api__workflow__organization",
+            ]
     """
 
     def filter_queryset(self, request, queryset, view):
-        if getattr(view, "skip_org_filter", False):
+        if getattr(view, SKIP_ORG_FILTER, False):
             return queryset
 
         model = queryset.model
@@ -43,6 +59,15 @@ def filter_queryset(self, request, queryset, view):
             )
             return queryset.none()
 
+        # Use explicit paths if set on the viewset (for models with
+        # multiple nullable FK paths to Organization).
+        explicit_paths = getattr(view, ORG_FILTER_PATHS, None)
+        if explicit_paths:
+            q = Q()
+            for path in explicit_paths:
+                q |= Q(**{path: org})
+            return queryset.filter(q)
+
         path = get_org_path(model)
         if path:
             return queryset.filter(**{path: org})