Fixed #27489 -- Renamed permissions upon model renaming in migrations.

2 files changed, 88 insertions, 3 deletions

diff --git a/django/contrib/auth/apps.py b/django/contrib/auth/apps.py
index ad6f816809..eeba5b7e13 100644
--- a/django/contrib/auth/apps.py
+++ b/django/contrib/auth/apps.py
@@ -1,12 +1,12 @@
 from django.apps import AppConfig
 from django.core import checks
 from django.db.models.query_utils import DeferredAttribute
-from django.db.models.signals import post_migrate
+from django.db.models.signals import post_migrate, pre_migrate
 from django.utils.translation import gettext_lazy as _
 
 from . import get_user_model
 from .checks import check_middleware, check_models_permissions, check_user_model
-from .management import create_permissions
+from .management import create_permissions, rename_permissions
 from .signals import user_logged_in
 
 
@@ -20,6 +20,11 @@ class AuthConfig(AppConfig):
             create_permissions,
             dispatch_uid="django.contrib.auth.management.create_permissions",
         )
+        pre_migrate.connect(
+            rename_permissions,
+            dispatch_uid="django.contrib.auth.management.rename_permissions",
+        )
+
         last_login_field = getattr(get_user_model(), "last_login", None)
         # Register the handler only if UserModel.last_login is a field.
         if isinstance(last_login_field, DeferredAttribute):
diff --git a/django/contrib/auth/management/__init__.py b/django/contrib/auth/management/__init__.py
index e816357b2b..40ada52e29 100644
--- a/django/contrib/auth/management/__init__.py
+++ b/django/contrib/auth/management/__init__.py
@@ -9,7 +9,9 @@ from django.apps import apps as global_apps
 from django.contrib.auth import get_permission_codename
 from django.contrib.contenttypes.management import create_contenttypes
 from django.core import exceptions
-from django.db import DEFAULT_DB_ALIAS, router
+from django.db import DEFAULT_DB_ALIAS, migrations, router, transaction
+from django.db.utils import IntegrityError
+from django.utils.text import camel_case_to_spaces
 
 
 def _get_all_permissions(opts):
@@ -108,6 +110,84 @@ def create_permissions(
             print("Adding permission '%s'" % perm)
 
 
+class RenamePermission(migrations.RunPython):
+    def __init__(self, app_label, old_model, new_model):
+        self.app_label = app_label
+        self.old_model = old_model
+        self.new_model = new_model
+        super(RenamePermission, self).__init__(
+            self.rename_forward, self.rename_backward
+        )
+
+    def _rename(self, apps, schema_editor, old_model, new_model):
+        ContentType = apps.get_model("contenttypes", "ContentType")
+        # Use the live Permission model instead of the frozen one, since frozen
+        # models do not retain foreign key constraints.
+        from django.contrib.auth.models import Permission
+
+        db = schema_editor.connection.alias
+        ctypes = ContentType.objects.filter(
+            app_label=self.app_label, model__icontains=old_model.lower()
+        )
+        for permission in Permission.objects.filter(
+            content_type_id__in=ctypes.values("id")
+        ):
+            prefix = permission.codename.split("_")[0]
+            default_verbose_name = camel_case_to_spaces(new_model)
+
+            new_codename = f"{prefix}_{new_model.lower()}"
+            new_name = f"Can {prefix} {default_verbose_name}"
+
+            if permission.codename != new_codename or permission.name != new_name:
+                permission.codename = new_codename
+                permission.name = new_name
+                try:
+                    with transaction.atomic(using=db):
+                        permission.save(update_fields={"name", "codename"})
+                except IntegrityError:
+                    pass
+
+    def rename_forward(self, apps, schema_editor):
+        self._rename(apps, schema_editor, self.old_model, self.new_model)
+
+    def rename_backward(self, apps, schema_editor):
+        self._rename(apps, schema_editor, self.new_model, self.old_model)
+
+
+def rename_permissions(
+    plan,
+    verbosity=2,
+    interactive=True,
+    using=DEFAULT_DB_ALIAS,
+    apps=global_apps,
+    **kwargs,
+):
+    """
+    Insert a `RenamePermissionType` operation after every planned `RenameModel`
+    operation.
+    """
+    try:
+        Permission = apps.get_model("auth", "Permission")
+    except LookupError:
+        return
+    else:
+        if not router.allow_migrate_model(using, Permission):
+            return
+
+    for migration, backward in plan:
+        inserts = []
+        for index, operation in enumerate(migration.operations):
+            if isinstance(operation, migrations.RenameModel):
+                operation = RenamePermission(
+                    migration.app_label,
+                    operation.old_name,
+                    operation.new_name,
+                )
+                inserts.append((index + 1, operation))
+        for inserted, (index, operation) in enumerate(inserts):
+            migration.operations.insert(inserted + index, operation)
+
+
 def get_system_username():
     """
     Return the current system user's username, or an empty string if the