Fixed #36984 -- Made inline formset error messages respect delete_confirmation_max_display.

Author: Karolis Ryselis

AUTHORS

@@ -600,6 +600,7 @@ answer newbie questions, and generally made Django that much better:
     Karderio <karderio@gmail.com>
     Karen Tracey <kmtracey@gmail.com>
     Karol Sikora <elektrrrus@gmail.com>
+    Karolis Ryselis <karolis.ryselis@gmail.com>
     Kasey Steinhauer <kstein257@gmail.com>
     Kasun Herath <kasunh01@gmail.com>
     Katherine “Kati” Michel <kthrnmichel@gmail.com>

django/contrib/admin/checks.py

@@ -190,6 +190,7 @@ def check(self, admin_obj, **kwargs):
             *self._check_view_on_site_url(admin_obj),
             *self._check_ordering(admin_obj),
             *self._check_readonly_fields(admin_obj),
+            *self._check_delete_confirmation_max_display(admin_obj),
         ]
 
     def _check_autocomplete_fields(self, obj):
@@ -824,6 +825,25 @@ def _check_readonly_fields_item(self, obj, field_name, label):
             else:
                 return []
 
+    def _check_delete_confirmation_max_display(self, obj):
+        """Check that delete_confirmation_max_display is
+        a non-negative integer or None."""
+
+        if obj.delete_confirmation_max_display is None:
+            return []
+        if (
+            not isinstance(obj.delete_confirmation_max_display, int)
+            or obj.delete_confirmation_max_display < 0
+        ):
+            return must_be(
+                "a non-negative integer or None",
+                option="delete_confirmation_max_display",
+                obj=obj,
+                id="admin.E041",
+            )
+        else:
+            return []
+
 
 class ModelAdminChecks(BaseModelAdminChecks):
     def check(self, admin_obj, **kwargs):
@@ -842,7 +862,6 @@ def check(self, admin_obj, **kwargs):
             *self._check_search_fields(admin_obj),
             *self._check_date_hierarchy(admin_obj),
             *self._check_actions(admin_obj),
-            *self._check_delete_confirmation_max_display(admin_obj),
         ]
 
     def _check_save_as(self, obj):
@@ -1093,25 +1112,6 @@ def _check_list_select_related(self, obj):
         else:
             return []
 
-    def _check_delete_confirmation_max_display(self, obj):
-        """Check that delete_confirmation_max_display is
-        a non-negative integer or None."""
-
-        if obj.delete_confirmation_max_display is None:
-            return []
-        if (
-            not isinstance(obj.delete_confirmation_max_display, int)
-            or obj.delete_confirmation_max_display < 0
-        ):
-            return must_be(
-                "a non-negative integer or None",
-                option="delete_confirmation_max_display",
-                obj=obj,
-                id="admin.E131",
-            )
-        else:
-            return []
-
     def _check_list_per_page(self, obj):
         """Check that list_per_page is an integer."""
 

django/contrib/admin/options.py

@@ -1,7 +1,9 @@
 import copy
 import enum
+import itertools
 import json
 import re
+import sys
 import warnings
 from collections.abc import Callable
 from dataclasses import dataclass
@@ -191,6 +193,7 @@ class BaseModelAdmin(metaclass=forms.MediaDefiningClass):
     view_on_site = True
     show_full_result_count = True
     checks_class = BaseModelAdminChecks
+    delete_confirmation_max_display = None
 
     def check(self, **kwargs):
         return self.checks_class().check(self, **kwargs)
@@ -704,7 +707,6 @@ class ModelAdmin(BaseModelAdmin):
     add_form_template = None
     change_form_template = None
     change_list_template = None
-    delete_confirmation_max_display = None
     delete_confirmation_template = None
     delete_selected_confirmation_template = None
     object_history_template = None
@@ -2755,6 +2757,11 @@ def get_formset(self, request, obj=None, **kwargs):
         base_model_form = defaults["form"]
         can_change = self.has_change_permission(request, obj) if request else True
         can_add = self.has_add_permission(request, obj) if request else True
+        delete_confirmation_max_display = (
+            self.delete_confirmation_max_display
+            if self.delete_confirmation_max_display
+            else sys.maxsize
+        )
 
         class DeleteProtectedModelForm(base_model_form):
             def hand_clean_DELETE(self):
@@ -2771,7 +2778,10 @@ def hand_clean_DELETE(self):
                     collector.collect([self.instance])
                     if collector.protected:
                         objs = []
-                        for p in collector.protected:
+                        protected = itertools.islice(
+                            collector.protected, delete_confirmation_max_display
+                        )
+                        for p in protected:
                             objs.append(
                                 # Translators: Model verbose name and instance
                                 # representation, suitable to be an item in a
@@ -2782,8 +2792,26 @@ def hand_clean_DELETE(self):
                         params = {
                             "class_name": self._meta.model._meta.verbose_name,
                             "instance": self.instance,
-                            "related_objects": get_text_list(objs, _("and")),
                         }
+                        remaining_object_count = (
+                            len(collector.protected) - delete_confirmation_max_display
+                        )
+                        if remaining_object_count > 0:
+                            # Translators: This string is used as a separator
+                            # between list elements
+                            related = (
+                                _(", ").join(str(i) for i in objs)
+                                + _(", ")
+                                + ngettext(
+                                    "…and %(count)d more object.",
+                                    "…and %(count)d more objects.",
+                                    remaining_object_count,
+                                )
+                                % {"count": remaining_object_count}
+                            )
+                        else:
+                            related = get_text_list(objs, _("and"))
+                        params["related_objects"] = related
                         msg = _(
                             "Deleting %(class_name)s %(instance)s would require "
                             "deleting the following protected related objects: "

docs/ref/checks.txt

@@ -759,6 +759,8 @@ with the admin site:
   referenced by ``<modeladmin>.autocomplete_fields``.
 * **admin.E040**: ``<modeladmin>`` must define ``search_fields``, because
   it's referenced by ``<other_modeladmin>.autocomplete_fields``.
+* **admin.E041**: The value of ``delete_confirmation_max_display`` must be a
+  non-negative integer or ``None``.
 
 ``ModelAdmin``
 ~~~~~~~~~~~~~~
@@ -819,8 +821,6 @@ with the admin site:
   method for the ``<action>`` action.
 * **admin.E130**: ``__name__`` attributes of actions defined in
   ``<modeladmin>`` must be unique. Name ``<name>`` is not unique.
-* **admin.E131**: The value of ``delete_confirmation_max_display`` must be a
-  non-negative integer or ``None``.
 
 ``InlineModelAdmin``
 ~~~~~~~~~~~~~~~~~~~~

docs/ref/contrib/admin/index.txt

@@ -1403,8 +1403,10 @@ default templates used by the :class:`ModelAdmin` views:
     relationship hierarchy. This is purely a display setting and does not
     affect the total number of objects retrieved from the database.
 
-    This applies to both :meth:`delete_view` and the ``delete_selected``
-    action. By default, this is ``None`` (no truncation).
+    This applies to :meth:`delete_view` and the ``delete_selected``
+    action if specified for ``ModelAdmin``, and to protected deletion
+    validation messages if specified for ``InlineModelAdmin``. By default,
+    this is ``None`` (no truncation).
 
 .. attribute:: ModelAdmin.object_history_template
 

docs/releases/6.1.txt

@@ -143,8 +143,8 @@ Minor features
 
 * The :attr:`~django.contrib.admin.ModelAdmin.delete_confirmation_max_display`
   option allows customizing how many objects are displayed on admin delete
-  confirmation pages before the remainder is truncated. The default is
-  ``None`` (no truncation).
+  confirmation pages and inline protected deletion errors before the remainder
+  is truncated. The default is ``None`` (no truncation).
 
 * In order to improve accessibility of the admin change forms:
 

tests/admin_inlines/admin.py

@@ -296,6 +296,7 @@ def call_me(self, obj):
 class ChapterInline(admin.TabularInline):
     model = Chapter
     readonly_fields = ["call_me"]
+    delete_confirmation_max_display = 3
 
     def call_me(self, obj):
         return "Callable in ChapterInline"

tests/admin_inlines/models.py

@@ -247,9 +247,7 @@ class Chapter(models.Model):
 
 
 class FootNote(models.Model):
-    """
-    Model added for ticket 19838
-    """
+    """Model for models.PROTECT."""
 
     chapter = models.ForeignKey(Chapter, models.PROTECT)
     note = models.CharField(max_length=40)

tests/admin_inlines/tests.py

@@ -830,6 +830,76 @@ def test_inlines_based_on_model_state(self):
         parent.refresh_from_db()
         self.assertIs(parent.show_inlines, True)
 
+    def test_delete_protected_message_limits_number_of_objects_displayed(self):
+        # admin limits the number of displayed objects to 2, so we create
+        # 5 footnotes.
+        novel = Novel.objects.create()
+        chapter = Chapter.objects.create(novel=novel)
+        footnotes = [FootNote(chapter=chapter) for i in range(5)]
+        FootNote.objects.bulk_create(footnotes)
+
+        response = self.client.post(
+            reverse("admin:admin_inlines_novel_change", args=(novel.pk,)),
+            data={
+                "show_inlines": "on",
+                "chapter_set-TOTAL_FORMS": "1",
+                "chapter_set-INITIAL_FORMS": "1",
+                "chapter_set-MAX_NUM_FORMS": "1000",
+                "chapter_set-MIN_NUM_FORMS": "0",
+                "chapter_set-0-id": chapter.id,
+                "chapter_set-0-name": chapter.name,
+                "chapter_set-0-novel": novel.id,
+                "chapter_set-0-DELETE": "on",
+            },
+        )
+        self.assertEqual(response.status_code, 200)
+        inline_formset = response.context_data["inline_admin_formsets"][0]
+        self.assertEqual(1, len(inline_formset.non_form_errors()))
+        error_message = inline_formset.non_form_errors()[0]
+        self.assertTrue(
+            error_message.startswith(
+                f"Deleting chapter Chapter object ({chapter.pk}) would "
+                "require deleting the following protected related objects:"
+            ),
+            error_message,
+        )
+        self.assertEqual(error_message.count("FootNote"), 3, error_message)
+        self.assertTrue(error_message.endswith("…and 2 more objects."), error_message)
+
+    def test_delete_protected_message_does_not_limit_small_amount_of_objects(self):
+        novel = Novel.objects.create()
+        chapter = Chapter.objects.create(novel=novel)
+        footnotes = [FootNote(chapter=chapter) for i in range(3)]
+        FootNote.objects.bulk_create(footnotes)
+
+        response = self.client.post(
+            reverse("admin:admin_inlines_novel_change", args=(novel.pk,)),
+            data={
+                "show_inlines": "on",
+                "chapter_set-TOTAL_FORMS": "1",
+                "chapter_set-INITIAL_FORMS": "1",
+                "chapter_set-MAX_NUM_FORMS": "1000",
+                "chapter_set-MIN_NUM_FORMS": "0",
+                "chapter_set-0-id": chapter.id,
+                "chapter_set-0-name": chapter.name,
+                "chapter_set-0-novel": novel.id,
+                "chapter_set-0-DELETE": "on",
+            },
+        )
+        self.assertEqual(response.status_code, 200)
+        inline_formset = response.context_data["inline_admin_formsets"][0]
+        self.assertEqual(1, len(inline_formset.non_form_errors()))
+        error_message = inline_formset.non_form_errors()[0]
+        self.assertTrue(
+            error_message.startswith(
+                f"Deleting chapter Chapter object ({chapter.pk}) would require "
+                "deleting the following protected related objects:"
+            ),
+            error_message,
+        )
+        self.assertEqual(error_message.count("FootNote object"), 3)
+        self.assertNotIn("more", error_message)
+
 
 @override_settings(ROOT_URLCONF="admin_inlines.urls")
 class TestInlineMedia(TestDataMixin, TestCase):

tests/modeladmin/test_checks.py

@@ -1033,7 +1033,7 @@ class TestModelAdmin(ModelAdmin):
                 "'delete_confirmation_max_display'"
                 " must be a non-negative integer or None."
             ),
-            "admin.E131",
+            "admin.E041",
         )
 
     def test_negative_integer(self):
@@ -1048,7 +1048,7 @@ class TestModelAdmin(ModelAdmin):
                 "'delete_confirmation_max_display'"
                 " must be a non-negative integer or None."
             ),
-            "admin.E131",
+            "admin.E041",
         )
 
     def test_valid_case(self):
@@ -1063,6 +1063,22 @@ class TestModelAdmin(ModelAdmin):
 
         self.assertIsValid(TestModelAdmin, ValidationTestModel)
 
+    def test_inline_not_integer(self):
+        class TestInlineModelAdmin(TabularInline):
+            delete_confirmation_max_display = "goodbye"
+            model = ValidationTestInlineModel
+
+        self.assertIsInvalid(
+            TestInlineModelAdmin,
+            ValidationTestModel,
+            (
+                "The value of "
+                "'delete_confirmation_max_display'"
+                " must be a non-negative integer or None."
+            ),
+            "admin.E041",
+        )
+
 
 class SearchFieldsCheckTests(CheckTestCase):
     def test_not_iterable(self):