♻️(backend) refactor list view to allow filtering other views

the "filter_queryset" method is called in the middle of the
"get_object" method. We use the "get_object" in actions like
"children", "tree", etc. which start by calling "get_object"
but return lists of documents.

We would like to apply filters to these views but the it didn't
work because the "get_object" method was also impacted by the
filters...

In a future PR, we should take control of the "get_object" method
and decouple all this. We need a quick solution to allow releasing
the hierchical documents feature in the frontend.

CHANGELOG.md

@@ -11,6 +11,8 @@ and this project adheres to
 ## Fixed
 - 🐛(frontend) remove scroll listener table content  #688
 - 🔒️(back) restrict access to favorite_list endpoint #690
+- 🐛(backend) refactor to fix filtering on children 
+    and descendants views #695
 
 
 ## [2.4.0] - 2025-03-06

src/backend/core/api/filters.py

@@ -12,15 +12,26 @@ class DocumentFilter(django_filters.FilterSet):
     Custom filter for filtering documents.
     """
 
+    title = django_filters.CharFilter(
+        field_name="title", lookup_expr="icontains", label=_("Title")
+    )
+
+    class Meta:
+        model = models.Document
+        fields = ["title"]
+
+
+class ListDocumentFilter(DocumentFilter):
+    """
+    Custom filter for filtering documents.
+    """
+
     is_creator_me = django_filters.BooleanFilter(
         method="filter_is_creator_me", label=_("Creator is me")
     )
     is_favorite = django_filters.BooleanFilter(
         method="filter_is_favorite", label=_("Favorite")
     )
-    title = django_filters.CharFilter(
-        field_name="title", lookup_expr="icontains", label=_("Title")
-    )
 
     class Meta:
         model = models.Document

src/backend/core/api/serializers.py

@@ -177,10 +177,7 @@ class ListDocumentSerializer(serializers.ModelSerializer):
         request = self.context.get("request")
 
         if request:
-            paths_links_mapping = self.context.get("paths_links_mapping", None)
-            return document.get_abilities(
-                request.user, paths_links_mapping=paths_links_mapping
-            )
+            return document.get_abilities(request.user)
 
         return {}
 

src/backend/core/api/viewsets.py

@@ -31,7 +31,7 @@ from core.services.ai_services import AIService
 from core.services.collaboration_services import CollaborationService
 
 from . import permissions, serializers, utils
-from .filters import DocumentFilter
+from .filters import DocumentFilter, ListDocumentFilter
 
 logger = logging.getLogger(__name__)
 
@@ -316,7 +316,6 @@ class DocumentViewSet(
     SerializerPerActionMixin,
     drf.mixins.CreateModelMixin,
     drf.mixins.DestroyModelMixin,
-    drf.mixins.ListModelMixin,
     drf.mixins.UpdateModelMixin,
     viewsets.GenericViewSet,
 ):
@@ -414,8 +413,6 @@ class DocumentViewSet(
     - Implements soft delete logic to retain document tree structures.
     """
 
-    filter_backends = [drf_filters.DjangoFilterBackend]
-    filterset_class = DocumentFilter
     metadata_class = DocumentMetadata
     ordering = ["-updated_at"]
     ordering_fields = ["created_at", "updated_at", "title"]
@@ -502,11 +499,42 @@ class DocumentViewSet(
         )
 
     def filter_queryset(self, queryset):
-        """Apply annotations and filters sequentially."""
-        filterset = DocumentFilter(
+        """Override to apply annotations to generic views."""
+        queryset = super().filter_queryset(queryset)
+        queryset = self.annotate_is_favorite(queryset)
+        queryset = self.annotate_user_roles(queryset)
+        return queryset
+
+    def get_response_for_queryset(self, queryset):
+        """Return paginated response for the queryset if requested."""
+        page = self.paginate_queryset(queryset)
+        if page is not None:
+            serializer = self.get_serializer(page, many=True)
+            return self.get_paginated_response(serializer.data)
+
+        serializer = self.get_serializer(queryset, many=True)
+        return drf.response.Response(serializer.data)
+
+    def list(self, request, *args, **kwargs):
+        """
+        Returns a DRF response containing the filtered, annotated and ordered document list.
+
+        This method applies filtering based on request parameters using `ListDocumentFilter`.
+        It performs early filtering on model fields, annotates user roles, and removes
+        descendant documents to keep only the highest ancestors readable by the current user.
+
+        Additional annotations (e.g., `is_highest_ancestor_for_user`, favorite status) are
+        applied before ordering and returning the response.
+        """
+        queryset = (
+            self.get_queryset()
+        )  # Not calling filter_queryset. We do our own cooking.
+
+        filterset = ListDocumentFilter(
             self.request.GET, queryset=queryset, request=self.request
         )
-        filterset.is_valid()
+        if not filterset.is_valid():
+            raise drf.exceptions.ValidationError(filterset.errors)
         filter_data = filterset.form.cleaned_data
 
         # Filter as early as possible on fields that are available on the model
@@ -515,22 +543,19 @@ class DocumentViewSet(
 
         queryset = self.annotate_user_roles(queryset)
 
-        if self.action == "list":
-            # Among the results, we may have documents that are ancestors/descendants
-            # of each other. In this case we want to keep only the highest ancestors.
-            root_paths = utils.filter_root_paths(
-                queryset.order_by("path").values_list("path", flat=True),
-                skip_sorting=True,
-            )
-            queryset = queryset.filter(path__in=root_paths)
+        # Among the results, we may have documents that are ancestors/descendants
+        # of each other. In this case we want to keep only the highest ancestors.
+        root_paths = utils.filter_root_paths(
+            queryset.order_by("path").values_list("path", flat=True),
+            skip_sorting=True,
+        )
+        queryset = queryset.filter(path__in=root_paths)
 
-            # Annotate the queryset with an attribute marking instances as highest ancestor
-            # in order to save some time while computing abilities on the instance
-            queryset = queryset.annotate(
-                is_highest_ancestor_for_user=db.Value(
-                    True, output_field=db.BooleanField()
-                )
-            )
+        # Annotate the queryset with an attribute marking instances as highest ancestor
+        # in order to save some time while computing abilities on the instance
+        queryset = queryset.annotate(
+            is_highest_ancestor_for_user=db.Value(True, output_field=db.BooleanField())
+        )
 
         # Annotate favorite status and filter if applicable as late as possible
         queryset = self.annotate_is_favorite(queryset)
@@ -539,18 +564,11 @@ class DocumentViewSet(
         )
 
         # Apply ordering only now that everyting is filtered and annotated
-        return filters.OrderingFilter().filter_queryset(self.request, queryset, self)
+        queryset = filters.OrderingFilter().filter_queryset(
+            self.request, queryset, self
+        )
 
-    def get_response_for_queryset(self, queryset):
-        """Return paginated response for the queryset if requested."""
-        page = self.paginate_queryset(queryset)
-        if page is not None:
-            serializer = self.get_serializer(page, many=True)
-            result = self.get_paginated_response(serializer.data)
-            return result
-
-        serializer = self.get_serializer(queryset, many=True)
-        return drf.response.Response(serializer.data)
+        return self.get_response_for_queryset(queryset)
 
     def retrieve(self, request, *args, **kwargs):
         """
@@ -604,7 +622,7 @@ class DocumentViewSet(
             user=user
         ).values_list("document_id", flat=True)
 
-        queryset = self.get_queryset()
+        queryset = self.filter_queryset(self.get_queryset())
         queryset = queryset.filter(id__in=favorite_documents_ids)
         return self.get_response_for_queryset(queryset)
 
@@ -731,7 +749,6 @@ class DocumentViewSet(
         detail=True,
         methods=["get", "post"],
         ordering=["path"],
-        url_path="children",
     )
     def children(self, request, *args, **kwargs):
         """Handle listing and creating children of a document"""
@@ -763,10 +780,35 @@ class DocumentViewSet(
             )
 
         # GET: List children
-        queryset = document.get_children().filter(deleted_at__isnull=True)
+        queryset = document.get_children().filter(ancestors_deleted_at__isnull=True)
         queryset = self.filter_queryset(queryset)
-        queryset = self.annotate_is_favorite(queryset)
-        queryset = self.annotate_user_roles(queryset)
+
+        filterset = DocumentFilter(request.GET, queryset=queryset)
+        if not filterset.is_valid():
+            raise drf.exceptions.ValidationError(filterset.errors)
+
+        queryset = filterset.qs
+
+        return self.get_response_for_queryset(queryset)
+
+    @drf.decorators.action(
+        detail=True,
+        methods=["get"],
+        ordering=["path"],
+    )
+    def descendants(self, request, *args, **kwargs):
+        """Handle listing descendants of a document"""
+        document = self.get_object()
+
+        queryset = document.get_descendants().filter(ancestors_deleted_at__isnull=True)
+        queryset = self.filter_queryset(queryset)
+
+        filterset = DocumentFilter(request.GET, queryset=queryset)
+        if not filterset.is_valid():
+            raise drf.exceptions.ValidationError(filterset.errors)
+
+        queryset = filterset.qs
+
         return self.get_response_for_queryset(queryset)
 
     @drf.decorators.action(

src/backend/core/models.py

@@ -809,17 +809,18 @@ class Document(MP_Node, BaseModel):
         Soft delete the document, marking the deletion on descendants.
         We still keep the .delete() method untouched for programmatic purposes.
         """
-        if self.deleted_at or self.ancestors_deleted_at:
+        if (
+            self._meta.model.objects.filter(
+                models.Q(deleted_at__isnull=False)
+                | models.Q(ancestors_deleted_at__isnull=False),
+                pk=self.pk,
+            ).exists()
+            or self.get_ancestors().filter(deleted_at__isnull=False).exists()
+        ):
             raise RuntimeError(
                 "This document is already deleted or has deleted ancestors."
             )
 
-        # Check if any ancestors are deleted
-        if self.get_ancestors().filter(deleted_at__isnull=False).exists():
-            raise RuntimeError(
-                "Cannot delete this document because one or more ancestors are already deleted."
-            )
-
         self.ancestors_deleted_at = self.deleted_at = timezone.now()
         self.save()
 
@@ -836,14 +837,8 @@ class Document(MP_Node, BaseModel):
             raise ValidationError({"deleted_at": [_("This document is not deleted.")]})
 
         if self.deleted_at < get_trashbin_cutoff():
-            raise ValidationError(
-                {
-                    "deleted_at": [
-                        _(
-                            "This document was permanently deleted and cannot be restored."
-                        )
-                    ]
-                }
+            raise RuntimeError(
+                "This document was permanently deleted and cannot be restored."
             )
 
         # save the current deleted_at value to exclude it from the descendants update

src/backend/core/tests/documents/test_api_documents_children_create.py

@@ -1,5 +1,5 @@
 """
-Tests for Documents API endpoint in impress's core app: create
+Tests for Documents API endpoint in impress's core app: children create
 """
 
 from uuid import uuid4

src/backend/core/tests/documents/test_api_documents_children_list.py

@@ -1,5 +1,5 @@
 """
-Tests for Documents API endpoint in impress's core app: retrieve
+Tests for Documents API endpoint in impress's core app: children list
 """
 
 import random