Reinstate nullable GroupPagePermission.permission_type and make Permission FK nullable

wagtail/migrations/0085_add_grouppagepermission_permission.py

@@ -10,6 +10,9 @@ class Migration(migrations.Migration):
         ("wagtailcore", "0084_add_default_page_permissions"),
     ]
 
+    # Add a nullable permission ForeignKey and make the old permission_type
+    # field nullable so both formats still work for the duration of the
+    # deprecation period.
     operations = [
         migrations.AddField(
             model_name="grouppagepermission",
@@ -22,23 +25,23 @@ class Migration(migrations.Migration):
                 verbose_name="permission",
             ),
         ),
-        # Make permission_type nullable so the RemoveField operation will be reversible
         migrations.AlterField(
             model_name="grouppagepermission",
             name="permission_type",
             field=models.CharField(
+                verbose_name="permission type",
                 null=True,
                 blank=True,
+                max_length=20,
                 choices=[
                     ("add", "Add/edit pages you own"),
-                    ("edit", "Edit any page"),
-                    ("publish", "Publish any page"),
                     ("bulk_delete", "Delete pages with children"),
+                    # Use "change" instead of "edit" to match Django's permission codename
+                    ("change", "Edit any page"),
                     ("lock", "Lock/unlock pages you've locked"),
+                    ("publish", "Publish any page"),
                     ("unlock", "Unlock any page"),
                 ],
-                max_length=20,
-                verbose_name="permission type",
             ),
         ),
     ]

wagtail/migrations/0087_grouppagepermission_use_django_permission.py

@@ -1,31 +0,0 @@
-# Generated by Django 4.2.1 on 2023-06-14 16:35
-
-from django.db import migrations, models
-import django.db.models.deletion
-
-
-class Migration(migrations.Migration):
-
-    dependencies = [
-        ("wagtailcore", "0086_populate_grouppagepermission_permission"),
-    ]
-
-    operations = [
-        migrations.AlterField(
-            model_name="grouppagepermission",
-            name="permission",
-            field=models.ForeignKey(
-                on_delete=django.db.models.deletion.CASCADE,
-                to="auth.permission",
-                verbose_name="permission",
-            ),
-        ),
-        migrations.AlterUniqueTogether(
-            name="grouppagepermission",
-            unique_together={("group", "page", "permission")},
-        ),
-        migrations.RemoveField(
-            model_name="grouppagepermission",
-            name="permission_type",
-        ),
-    ]

wagtail/models/__init__.py

@@ -1110,6 +1110,10 @@ PAGE_PERMISSION_TYPES = [
     ("unlock_page", _("Unlock"), _("Unlock any page")),
 ]
 
+PAGE_PERMISSION_TYPE_CHOICES = [
+    (identifier[:-5], long_label) for identifier, _, long_label in PAGE_PERMISSION_TYPES
+]
+
 PAGE_PERMISSION_CODENAMES = [identifier for identifier, *_ in PAGE_PERMISSION_TYPES]
 
 
@@ -2928,13 +2932,22 @@ class GroupPagePermission(models.Model):
     permission = models.ForeignKey(
         Permission,
         verbose_name=_("permission"),
+        null=True,
+        blank=True,
         on_delete=models.CASCADE,
     )
+    permission_type = models.CharField(
+        verbose_name=_("permission type"),
+        null=True,
+        blank=True,
+        max_length=20,
+        choices=PAGE_PERMISSION_TYPE_CHOICES,
+    )
 
     objects = GroupPagePermissionManager()
 
     class Meta:
-        unique_together = ("group", "page", "permission")
+        unique_together = ("group", "page", "permission_type")
         verbose_name = _("group page permission")
         verbose_name_plural = _("group page permissions")