Assert permission assignment does not scale with selection size

The two batching tests only checked that permissions came out correct at
5 and 50 objects, so reverting to the old per-object loop would still
have passed.  Check sizes as well to prevent that

src/documents/bulk_edit.py

@@ -28,7 +28,7 @@ from documents.models import DocumentType
 from documents.models import PaperlessTask
 from documents.models import StoragePath
 from documents.models import Tag
-from documents.permissions import set_permissions_for_object
+from documents.permissions import set_permissions_for_objects
 from documents.plugins.helpers import DocumentsStatusManager
 from documents.tasks import bulk_update_documents
 from documents.tasks import consume_file
@@ -431,10 +431,13 @@ def set_permissions(
     else:
         qs.update(owner=owner)
 
-    for doc in qs:
-        set_permissions_for_object(permissions=set_permissions, object=doc, merge=merge)
-
     affected_docs = list(qs.values_list("pk", flat=True))
+    set_permissions_for_objects(
+        permissions=set_permissions,
+        model=Document,
+        pks=affected_docs,
+        merge=merge,
+    )
 
     bulk_update_documents.apply_async(
         kwargs={"document_ids": affected_docs},

src/documents/permissions.py

@@ -173,6 +173,179 @@ def set_permissions_for_object(
                         )
 
 
+def _resolve_permissions(codenames: set[str], ctype: ContentType) -> list[Permission]:
+    """
+    Resolves `codenames` to Permission rows, raising like the single-object
+    assign_perm() this bulk path replaces does (via a `.get()` internally)
+    if any codename doesn't exist -- e.g. a client-supplied action name that
+    was never validated (BulkEditObjectsSerializer._validate_permissions
+    calls validate_set_permissions() only for its side-effecting id checks
+    and discards the filtered dict it returns, so an unrecognized action key
+    reaches this function as-is). A plain `.filter()` with no existence
+    check would otherwise silently build zero rows and no-op instead of
+    reporting the bad input.
+    """
+    permission_objs = list(
+        Permission.objects.filter(content_type=ctype, codename__in=codenames),
+    )
+    missing = codenames - {p.codename for p in permission_objs}
+    if missing:
+        raise Permission.DoesNotExist(
+            f"Permission matching query does not exist for codename(s): "
+            f"{', '.join(sorted(missing))}",
+        )
+    return permission_objs
+
+
+def _apply_bulk_permission_entry(
+    *,
+    perm_model: type[UserObjectPermission] | type[GroupObjectPermission],
+    identity_model: type[User] | type[Group],
+    identity_field: str,
+    ids: list[int],
+    codename: str,
+    permission_objs: list[Permission],
+    ctype: ContentType,
+    object_pks: list[str],
+    merge: bool,
+) -> None:
+    # Only the ids are needed to build permission rows (via `<field>_id=`),
+    # so avoid fetching full User/Group rows for identities that may not
+    # even end up being granted anything new.
+    add_ids = set(
+        identity_model.objects.filter(id__in=ids).values_list("id", flat=True),
+    )
+
+    if not merge:
+        existing_ids = set(
+            perm_model.objects.filter(
+                content_type=ctype,
+                object_pk__in=object_pks,
+                permission__codename=codename,
+            )
+            .values_list(f"{identity_field}_id", flat=True)
+            .distinct(),
+        )
+        remove_ids = existing_ids - add_ids
+        if remove_ids:
+            perm_model.objects.filter(
+                content_type=ctype,
+                object_pk__in=object_pks,
+                permission__codename=codename,
+                **{f"{identity_field}_id__in": remove_ids},
+            ).delete()
+
+    if not add_ids:
+        return
+
+    rows = [
+        perm_model(
+            content_type=ctype,
+            object_pk=pk,
+            permission=permission_obj,
+            **{f"{identity_field}_id": identity_id},
+        )
+        for permission_obj in permission_objs
+        for pk in object_pks
+        for identity_id in add_ids
+    ]
+    # ignore_conflicts skips only rows that already exist as an exact
+    # (identity, permission, object) match -- the same de-dup the
+    # underlying (user|group, permission, object_pk) unique constraint
+    # already enforces for the single-object assign_perm() this replaces,
+    # so it doesn't change what counts as "already granted". batch_size
+    # caps how many rows go into a single INSERT statement.
+    perm_model.objects.bulk_create(rows, ignore_conflicts=True, batch_size=1000)
+
+
+def set_permissions_for_objects(
+    permissions: dict,
+    model: type[Model],
+    pks: QuerySet | list,
+    *,
+    merge: bool = False,
+) -> None:
+    """
+    Bulk equivalent of set_permissions_for_object: applies the same
+    permission changes to every object identified by `pks` at once.
+
+    Takes a model + pks (rather than model instances) deliberately -- the
+    permission rows built below only ever need `pk`, `content_type`, and
+    identity ids, so callers shouldn't have to fetch full rows (with every
+    other field) just to hand them to this function.
+
+    Deliberately does not use guardian's queryset/list-aware assign_perm:
+    passing a list as the object routes to bulk_assign_perm, which skips
+    creating a direct permission row for anyone who already has the
+    permission via ANY group membership (it checks
+    ObjectPermissionChecker.has_perm, which is group-inheritance-aware) --
+    unlike the single-object assign_perm this replaces, which always
+    ensures a direct row via get_or_create regardless of group-derived
+    access. Losing that guarantee would mean a later revocation of the
+    group's grant silently strips access an admin explicitly asked to be
+    direct. Bulk-creating rows straight against the permission models
+    instead (see _apply_bulk_permission_entry) preserves the original
+    always-create-a-direct-row semantics while still batching every object
+    and every identity into one query per action, rather than one query per
+    (object, user) pair.
+    """
+    object_pks = [str(pk) for pk in pks]
+    if not object_pks:  # pragma: no cover
+        return
+
+    model_name = model.__name__.lower()
+    ctype = ContentType.objects.get_for_model(model)
+
+    # Every action is resolved up front, before anything is written, so an
+    # unrecognized action name (see _resolve_permissions) aborts the whole
+    # call instead of leaving the actions ahead of it already applied --
+    # BulkEditObjectsSerializer lets unknown keys through and its view turns
+    # the exception into a 400, so a half-applied change would otherwise be
+    # reported to the client as a failure.
+    permissions_by_action: dict[str, list[Permission]] = {}
+    for action, entry in permissions.items():
+        if "users" not in entry and "groups" not in entry:
+            continue
+        implied_codenames = {f"{action}_{model_name}"}
+        if action == "change":
+            # change gives view too
+            implied_codenames.add(f"view_{model_name}")
+        permissions_by_action[action] = _resolve_permissions(
+            implied_codenames,
+            ctype,
+        )
+
+    for action, entry in permissions.items():
+        codename = f"{action}_{model_name}"
+        permission_objs = permissions_by_action.get(action, [])
+
+        if "users" in entry:
+            _apply_bulk_permission_entry(
+                perm_model=UserObjectPermission,
+                identity_model=User,
+                identity_field="user",
+                ids=entry["users"],
+                codename=codename,
+                permission_objs=permission_objs,
+                ctype=ctype,
+                object_pks=object_pks,
+                merge=merge,
+            )
+
+        if "groups" in entry:
+            _apply_bulk_permission_entry(
+                perm_model=GroupObjectPermission,
+                identity_model=Group,
+                identity_field="group",
+                ids=entry["groups"],
+                codename=codename,
+                permission_objs=permission_objs,
+                ctype=ctype,
+                object_pks=object_pks,
+                merge=merge,
+            )
+
+
 def permitted_object_ids(
     user: User | None,
     model: type[Model],

src/documents/tests/test_api_objects.py

@@ -2,10 +2,15 @@ import datetime
 import json
 from unittest import mock
 
+from django.contrib.auth.models import Group
 from django.contrib.auth.models import Permission
 from django.contrib.auth.models import User
+from django.db import connection
 from django.test import override_settings
+from django.test.utils import CaptureQueriesContext
 from guardian.shortcuts import assign_perm
+from guardian.shortcuts import get_groups_with_perms
+from guardian.shortcuts import get_users_with_perms
 from rest_framework import status
 from rest_framework.test import APITestCase
 
@@ -842,6 +847,66 @@ class TestBulkEditObjects(APITestCase):
         self.assertEqual(response.status_code, status.HTTP_200_OK)
         self.assertEqual(StoragePath.objects.count(), 0)
 
+    def test_bulk_objects_set_permissions_batched_across_object_count(
+        self,
+    ) -> None:
+        """
+        GIVEN:
+            - Many tags are being bulk-edited to set permissions at once
+        WHEN:
+            - bulk_edit_objects API endpoint is called with set_permissions
+              operation over a small batch vs. a much larger one
+        THEN:
+            - Permissions are applied correctly at both scales
+            - Query count does not grow with the number of tags, i.e. each
+              user/group is applied across all tags with one batched call
+              rather than one call per (tag, identity) pair
+        """
+        group1 = Group.objects.create(name="perm-group")
+        permissions = {
+            "view": {"users": [self.user1.id, self.user2.id], "groups": [group1.id]},
+            "change": {"users": [self.user1.id], "groups": [group1.id]},
+        }
+
+        def run_with_n_tags(n: int) -> int:
+            tags = [Tag.objects.create(name=f"perm-tag-{n}-{i}") for i in range(n)]
+            with CaptureQueriesContext(connection) as ctx:
+                response = self.client.post(
+                    "/api/bulk_edit_objects/",
+                    json.dumps(
+                        {
+                            "objects": [t.id for t in tags],
+                            "object_type": "tags",
+                            "operation": "set_permissions",
+                            "permissions": permissions,
+                            "merge": False,
+                        },
+                    ),
+                    content_type="application/json",
+                )
+            self.assertEqual(response.status_code, status.HTTP_200_OK)
+            for tag in tags:
+                self.assertEqual(get_users_with_perms(tag).count(), 2)
+                self.assertEqual(get_groups_with_perms(tag).count(), 1)
+            return len(ctx.captured_queries)
+
+        small_batch_queries = run_with_n_tags(5)
+        large_batch_queries = run_with_n_tags(50)
+
+        # A tolerance rather than equality, matching the N+1 check in
+        # test_views.py: bulk_create's batch_size caps rows per INSERT, so a
+        # large enough selection does legitimately add statements, and the
+        # per-process ContentType cache makes the first run carry an extra
+        # query. Neither can hide a regression to per-object assignment,
+        # which would be ~10x the small-batch count here.
+        self.assertLessEqual(
+            large_batch_queries,
+            small_batch_queries + 5,
+            "Permission assignment appears to scale with object count: "
+            f"{small_batch_queries} queries for 5 tags vs. "
+            f"{large_batch_queries} for 50",
+        )
+
     def test_bulk_objects_delete_all_filtered(self) -> None:
         """
         GIVEN:

src/documents/tests/test_bulk_edit.py

@@ -5,8 +5,11 @@ from unittest import mock
 
 import pikepdf
 from django.contrib.auth.models import Group
+from django.contrib.auth.models import Permission
 from django.contrib.auth.models import User
+from django.db import connection
 from django.test import TestCase
+from django.test.utils import CaptureQueriesContext
 from guardian.shortcuts import assign_perm
 from guardian.shortcuts import get_groups_with_perms
 from guardian.shortcuts import get_users_with_perms
@@ -19,6 +22,7 @@ from documents.models import Document
 from documents.models import DocumentType
 from documents.models import StoragePath
 from documents.models import Tag
+from documents.permissions import set_permissions_for_objects
 from documents.tests.utils import DirectoriesMixin
 
 
@@ -515,6 +519,178 @@ class TestBulkEdit(DirectoriesMixin, TestCase):
         )
         self.assertEqual(groups_with_perms.count(), 2)
 
+    @mock.patch("documents.tasks.bulk_update_documents.apply_async")
+    def test_set_permissions_batched_across_document_count(
+        self,
+        m,
+    ) -> None:
+        """
+        GIVEN:
+            - Many documents are being bulk-edited to set permissions at once
+        WHEN:
+            - set_permissions runs over a small batch vs. a much larger one
+        THEN:
+            - Permissions are applied correctly at both scales
+            - Query count does not grow with the number of documents, i.e.
+              each user/group is applied across all documents with one
+              batched call rather than one call per (document, identity)
+              pair
+        """
+        permissions = {
+            "view": {
+                "users": [self.user1.id, self.user2.id],
+                "groups": [self.group2.id],
+            },
+            "change": {
+                "users": [self.user1.id],
+                "groups": [self.group2.id],
+            },
+        }
+
+        def run_with_n_documents(n: int) -> int:
+            docs = [
+                Document.objects.create(checksum=f"perm-{n}-{i}", title=f"perm-{n}-{i}")
+                for i in range(n)
+            ]
+            with CaptureQueriesContext(connection) as ctx:
+                bulk_edit.set_permissions(
+                    [doc.id for doc in docs],
+                    set_permissions=permissions,
+                    owner=self.owner,
+                    merge=False,
+                )
+            for doc in docs:
+                self.assertEqual(get_users_with_perms(doc).count(), 2)
+                self.assertEqual(get_groups_with_perms(doc).count(), 1)
+            return len(ctx.captured_queries)
+
+        small_batch_queries = run_with_n_documents(5)
+        large_batch_queries = run_with_n_documents(50)
+
+        # A tolerance rather than equality, matching the N+1 check in
+        # test_views.py: bulk_create's batch_size caps rows per INSERT, so a
+        # large enough selection does legitimately add statements, and the
+        # per-process ContentType cache makes the first run carry an extra
+        # query. Neither can hide a regression to per-document assignment,
+        # which would be ~10x the small-batch count here.
+        self.assertLessEqual(
+            large_batch_queries,
+            small_batch_queries + 5,
+            "Permission assignment appears to scale with document count: "
+            f"{small_batch_queries} queries for 5 documents vs. "
+            f"{large_batch_queries} for 50",
+        )
+
+    @mock.patch("documents.tasks.bulk_update_documents.apply_async")
+    def test_set_permissions_grants_direct_perm_even_if_already_granted_via_group(
+        self,
+        m,
+    ) -> None:
+        """
+        GIVEN:
+            - A user already has view access to a document via group
+              membership, with no direct grant of their own
+        WHEN:
+            - set_permissions explicitly grants that same user direct view
+              access via bulk_edit
+        THEN:
+            - A direct permission grant is created for the user, not skipped
+              because they already have equivalent access via the group
+
+        Regression test: guardian's queryset-aware assign_perm() (routed to
+        when the target is a list/queryset) skips creating a direct row for
+        anyone whose ObjectPermissionChecker.has_perm() already returns True
+        -- which includes group-derived access. The single-object assign_perm
+        this bulk path replaces has no such check; it always ensures a
+        direct row via get_or_create. Losing that guarantee would mean
+        revoking the group's grant later silently strips access that was
+        supposed to be explicit.
+        """
+        self.doc1.owner = self.user1
+        self.doc1.save()
+        self.user1.groups.add(self.group1)
+        assign_perm("view_document", self.group1, self.doc1)
+
+        bulk_edit.set_permissions(
+            [self.doc1.id],
+            set_permissions={
+                "view": {"users": [self.user1.id], "groups": []},
+            },
+            merge=True,
+        )
+
+        direct_users = get_users_with_perms(
+            self.doc1,
+            only_with_perms_in=["view_document"],
+            with_group_users=False,
+        )
+        self.assertIn(self.user1, direct_users)
+
+    def test_set_permissions_for_objects_raises_for_unknown_action(self) -> None:
+        """
+        GIVEN:
+            - An unrecognized permission action name with users to grant it
+              to
+        WHEN:
+            - set_permissions_for_objects is called
+        THEN:
+            - Permission.DoesNotExist is raised, not a silent no-op
+
+        Regression test: the endpoint that calls this
+        (BulkEditObjectPermissionsView) never actually validates action
+        names against the raw client-supplied permissions dict --
+        BulkEditObjectsSerializer._validate_permissions calls
+        validate_set_permissions() only for its side-effecting user/group id
+        checks and discards the filtered dict it returns -- so a bogus
+        action key reaches this function as-is. Resolving the Permission via
+        a bare `.filter()` (which returns empty instead of raising) would
+        silently drop the grant and report success.
+        """
+        with self.assertRaises(Permission.DoesNotExist):
+            set_permissions_for_objects(
+                {"not_a_real_action": {"users": [self.user1.id], "groups": []}},
+                Document,
+                [self.doc1.pk],
+            )
+
+    def test_set_permissions_for_objects_unknown_action_applies_nothing(
+        self,
+    ) -> None:
+        """
+        GIVEN:
+            - A permissions dict with a valid action ordered ahead of an
+              unrecognized one
+        WHEN:
+            - set_permissions_for_objects is called
+        THEN:
+            - Permission.DoesNotExist is raised
+            - The valid action ahead of it is not applied either
+
+        Every action is resolved before any row is written, so a bad action
+        name cannot leave a half-applied change behind. That matters because
+        BulkEditObjectsView turns this exception into a 400: without the
+        up-front resolution the client would be told the request failed
+        while the leading action had already been committed.
+        """
+        with self.assertRaises(Permission.DoesNotExist):
+            set_permissions_for_objects(
+                {
+                    "view": {"users": [self.user1.id], "groups": []},
+                    "not_a_real_action": {"users": [self.user1.id], "groups": []},
+                },
+                Document,
+                [self.doc1.pk],
+            )
+
+        self.assertNotIn(
+            self.user1,
+            get_users_with_perms(
+                self.doc1,
+                only_with_perms_in=["view_document"],
+                with_group_users=False,
+            ),
+        )
+
     @mock.patch("documents.models.Document.delete")
     def test_delete_documents_old_uuid_field(self, m) -> None:
         m.side_effect = Exception("Data too long for column 'transaction_id' at row 1")

src/documents/views.py

@@ -179,7 +179,7 @@ from documents.permissions import has_perms_owner_aware
 from documents.permissions import has_system_status_permission
 from documents.permissions import permitted_document_ids
 from documents.permissions import permitted_object_ids
-from documents.permissions import set_permissions_for_object
+from documents.permissions import set_permissions_for_objects
 from documents.permissions import user_is_unrestricted
 from documents.plugins.date_parsing import get_date_parser
 from documents.schema import generate_object_with_permissions_schema
@@ -4967,12 +4967,12 @@ class BulkEditObjectsView(PassUserMixin):
                     qs_owner_update.update(owner=owner)
 
                 if "permissions" in serializer.validated_data:
-                    for obj in qs:
-                        set_permissions_for_object(
-                            permissions=permissions,
-                            object=obj,
-                            merge=merge,
-                        )
+                    set_permissions_for_objects(
+                        permissions=permissions,
+                        model=object_class,
+                        pks=qs.values_list("pk", flat=True),
+                        merge=merge,
+                    )
 
             except Exception as e:
                 logger.warning(