Allow Page.permissions_for_user() to be overridden by specific page types

CHANGELOG.txt

@@ -10,6 +10,7 @@ Changelog
  * Improve layout and accessibility of the image URL generator page, reduce reliance on JavaScript (Temidayo Azeez)
  * Allow `UniqueConstraint` in place of `unique_together` for `TranslatableMixin`'s system check (Temidayo Azeez, Sage Abdullah)
  * Make use of `IndexView.get_add_url()` in snippets index view template (Christer Jensen, Sage Abdullah)
+ * Allow `Page.permissions_for_user()` to be overridden by specific page types (Sébastien Corbin)
  * Fix: Update system check for overwriting storage backends to recognise the `STORAGES` setting introduced in Django 4.2 (phijma-leukeleu)
  * Fix: Prevent password change form from raising a validation error when browser autocomplete fills in the "Old password" field (Chiemezuo Akujobi)
  * Fix: Ensure that the legacy dropdown options, when closed, do not get accidentally clicked by other interactions wide viewports (CheesyPhoenix, Christer Jensen)

docs/releases/6.0.md

@@ -20,6 +20,7 @@ depth: 1
  * Improve layout and accessibility of the image URL generator page, reduce reliance on JavaScript (Temidayo Azeez)
  * Allow `UniqueConstraint` in place of `unique_together` for {class}`~wagtail.models.TranslatableMixin`'s system check (Temidayo Azeez, Sage Abdullah)
  * Make use of `IndexView.get_add_url()` in snippets index view template (Christer Jensen, Sage Abdullah)
+ * Allow `Page.permissions_for_user()` to be overridden by specific page types (Sébastien Corbin)
 
 ### Bug fixes
 

wagtail/models/__init__.py

@@ -2377,6 +2377,17 @@ class Page(AbstractPage, index.Indexed, ClusterableModel, metaclass=PageBase):
         """
         Return a PagePermissionsTester object defining what actions the user can perform on this page
         """
+        # Allow specific classes to override this method, but only cast to the
+        # specific instance if it's not already specific and if the method has
+        # been overridden. This helps improve performance when working with
+        # base Page querysets.
+        is_overridden = (
+            self.specific_class
+            and self.specific_class.permissions_for_user
+            != type(self).permissions_for_user
+        )
+        if is_overridden and not isinstance(self, self.specific_class):
+            return self.specific_deferred.permissions_for_user(user)
         return PagePermissionTester(user, self)
 
     def is_previewable(self):

wagtail/test/testapp/migrations/0032_custompermissionpage.py

@@ -0,0 +1,35 @@
+# Generated by Django 4.2.3 on 2023-07-19 12:59
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("wagtailcore", "0088_fix_log_entry_json_timestamps"),
+        ("tests", "0031_searchtestmodel"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="CustomPermissionPage",
+            fields=[
+                (
+                    "page_ptr",
+                    models.OneToOneField(
+                        auto_created=True,
+                        on_delete=django.db.models.deletion.CASCADE,
+                        parent_link=True,
+                        primary_key=True,
+                        serialize=False,
+                        to="wagtailcore.page",
+                    ),
+                ),
+            ],
+            options={
+                "abstract": False,
+            },
+            bases=("wagtailcore.page",),
+        ),
+    ]

wagtail/test/testapp/models.py

@@ -70,6 +70,7 @@ from wagtail.models import (
     Orderable,
     Page,
     PageManager,
+    PagePermissionTester,
     PageQuerySet,
     PreviewableMixin,
     RevisionMixin,
@@ -2189,3 +2190,12 @@ class SearchTestModel(models.Model):
 
     def __str__(self):
         return self.title
+
+
+class CustomPermissionTester(PagePermissionTester):
+    pass
+
+
+class CustomPermissionPage(Page):
+    def permissions_for_user(self, user):
+        return CustomPermissionTester(user, self)

wagtail/tests/test_page_permissions.py

@@ -16,6 +16,8 @@ from wagtail.models import (
 from wagtail.permission_policies.pages import PagePermissionPolicy
 from wagtail.test.testapp.models import (
     BusinessSubIndex,
+    CustomPermissionPage,
+    CustomPermissionTester,
     EventIndex,
     EventPage,
     SingletonPageViaMaxCount,
@@ -844,6 +846,17 @@ class TestPagePermission(TestCase):
         self.assertFalse(editor_perms.can_lock())
         self.assertFalse(editor_perms.can_unlock())
 
+    def test_custom_permission_tester_page(self):
+        homepage = Page.objects.get(url_path="/home/")
+        instance = CustomPermissionPage(
+            title="This page has a custom permission tester",
+            slug="page-with-custom-permission-tester",
+        )
+        homepage.add_child(instance=instance)
+        page = Page.objects.get(pk=instance.pk)
+        user = get_user_model().objects.get(email="eventeditor@example.com")
+        self.assertIsInstance(page.permissions_for_user(user), CustomPermissionTester)
+
 
 class TestPagePermissionTesterCanCopyTo(TestCase):
     """Tests PagePermissionTester.can_copy_to()"""