[2.2.x] Fixed #31021 -- Fixed proxy model permissions data migration crash with a multiple databases setup.

Regression in 98296f86b340c8c9c968375d59f1d3a3479e60c2.

Backport of e8fcdaad5c428878d0a5d6ba820d957013f75595 from master

3 files changed, 66 insertions, 20 deletions

diff --git a/django/contrib/auth/migrations/0011_update_proxy_permissions.py b/django/contrib/auth/migrations/0011_update_proxy_permissions.py
index c3f617f438..7409ea1254 100644
--- a/django/contrib/auth/migrations/0011_update_proxy_permissions.py
+++ b/django/contrib/auth/migrations/0011_update_proxy_permissions.py
@@ -23,6 +23,7 @@ def update_proxy_model_permissions(apps, schema_editor, reverse=False):
     style = color_style()
     Permission = apps.get_model('auth', 'Permission')
     ContentType = apps.get_model('contenttypes', 'ContentType')
+    alias = schema_editor.connection.alias
     for Model in apps.get_models():
         opts = Model._meta
         if not opts.proxy:
@@ -34,13 +35,14 @@ def update_proxy_model_permissions(apps, schema_editor, reverse=False):
         permissions_query = Q(codename__in=proxy_default_permissions_codenames)
         for codename, name in opts.permissions:
             permissions_query = permissions_query | Q(codename=codename, name=name)
-        concrete_content_type = ContentType.objects.get_for_model(Model, for_concrete_model=True)
-        proxy_content_type = ContentType.objects.get_for_model(Model, for_concrete_model=False)
+        content_type_manager = ContentType.objects.db_manager(alias)
+        concrete_content_type = content_type_manager.get_for_model(Model, for_concrete_model=True)
+        proxy_content_type = content_type_manager.get_for_model(Model, for_concrete_model=False)
         old_content_type = proxy_content_type if reverse else concrete_content_type
         new_content_type = concrete_content_type if reverse else proxy_content_type
         try:
-            with transaction.atomic():
-                Permission.objects.filter(
+            with transaction.atomic(using=alias):
+                Permission.objects.using(alias).filter(
                     permissions_query,
                     content_type=old_content_type,
                 ).update(content_type=new_content_type)
diff --git a/docs/releases/2.2.8.txt b/docs/releases/2.2.8.txt
index e9bd1ed1cb..4d8f9869c5 100644
--- a/docs/releases/2.2.8.txt
+++ b/docs/releases/2.2.8.txt
@@ -13,3 +13,7 @@ Bugfixes
 * Fixed a data loss possibility in the admin changelist view when a custom
   :ref:`formset's prefix <formset-prefix>` contains regular expression special
   characters, e.g. `'$'` (:ticket:`31031`).
+
+* Fixed a regression in Django 2.2.1 that caused a crash when migrating
+  permissions for proxy models with a multiple database setup if the
+  ``default`` entry was empty (:ticket:`31021`).
diff --git a/tests/auth_tests/test_migrations.py b/tests/auth_tests/test_migrations.py
index 98c5b5964a..a91b9a9146 100644
--- a/tests/auth_tests/test_migrations.py
+++ b/tests/auth_tests/test_migrations.py
@@ -3,7 +3,8 @@ from importlib import import_module
 from django.apps import apps
 from django.contrib.auth.models import Permission, User
 from django.contrib.contenttypes.models import ContentType
-from django.test import TestCase
+from django.db import connection, connections
+from django.test import TransactionTestCase
 from django.test.utils import captured_stdout
 
 from .models import Proxy, UserProxy
@@ -11,7 +12,7 @@ from .models import Proxy, UserProxy
 update_proxy_permissions = import_module('django.contrib.auth.migrations.0011_update_proxy_permissions')
 
 
-class ProxyModelWithDifferentAppLabelTests(TestCase):
+class ProxyModelWithDifferentAppLabelTests(TransactionTestCase):
     available_apps = [
         'auth_tests',
         'django.contrib.auth',
@@ -41,7 +42,8 @@ class ProxyModelWithDifferentAppLabelTests(TestCase):
         proxy_model_content_type = ContentType.objects.get_for_model(UserProxy, for_concrete_model=False)
         self.assertEqual(self.default_permission.content_type, self.concrete_content_type)
         self.assertEqual(self.custom_permission.content_type, self.concrete_content_type)
-        update_proxy_permissions.update_proxy_model_permissions(apps, None)
+        with connection.schema_editor() as editor:
+            update_proxy_permissions.update_proxy_model_permissions(apps, editor)
         self.default_permission.refresh_from_db()
         self.assertEqual(self.default_permission.content_type, proxy_model_content_type)
         self.custom_permission.refresh_from_db()
@@ -54,7 +56,8 @@ class ProxyModelWithDifferentAppLabelTests(TestCase):
         for permission in [self.default_permission, self.custom_permission]:
             self.assertTrue(user.has_perm('auth.' + permission.codename))
             self.assertFalse(user.has_perm('auth_tests.' + permission.codename))
-        update_proxy_permissions.update_proxy_model_permissions(apps, None)
+        with connection.schema_editor() as editor:
+            update_proxy_permissions.update_proxy_model_permissions(apps, editor)
         # Reload user to purge the _perm_cache.
         user = User._default_manager.get(pk=user.pk)
         for permission in [self.default_permission, self.custom_permission]:
@@ -62,8 +65,9 @@ class ProxyModelWithDifferentAppLabelTests(TestCase):
             self.assertTrue(user.has_perm('auth_tests.' + permission.codename))
 
     def test_migrate_backwards(self):
-        update_proxy_permissions.update_proxy_model_permissions(apps, None)
-        update_proxy_permissions.revert_proxy_model_permissions(apps, None)
+        with connection.schema_editor() as editor:
+            update_proxy_permissions.update_proxy_model_permissions(apps, editor)
+            update_proxy_permissions.revert_proxy_model_permissions(apps, editor)
         self.default_permission.refresh_from_db()
         self.assertEqual(self.default_permission.content_type, self.concrete_content_type)
         self.custom_permission.refresh_from_db()
@@ -76,8 +80,9 @@ class ProxyModelWithDifferentAppLabelTests(TestCase):
         for permission in [self.default_permission, self.custom_permission]:
             self.assertTrue(user.has_perm('auth.' + permission.codename))
             self.assertFalse(user.has_perm('auth_tests.' + permission.codename))
-        update_proxy_permissions.update_proxy_model_permissions(apps, None)
-        update_proxy_permissions.revert_proxy_model_permissions(apps, None)
+        with connection.schema_editor() as editor:
+            update_proxy_permissions.update_proxy_model_permissions(apps, editor)
+            update_proxy_permissions.revert_proxy_model_permissions(apps, editor)
         # Reload user to purge the _perm_cache.
         user = User._default_manager.get(pk=user.pk)
         for permission in [self.default_permission, self.custom_permission]:
@@ -85,7 +90,7 @@ class ProxyModelWithDifferentAppLabelTests(TestCase):
             self.assertFalse(user.has_perm('auth_tests.' + permission.codename))
 
 
-class ProxyModelWithSameAppLabelTests(TestCase):
+class ProxyModelWithSameAppLabelTests(TransactionTestCase):
     available_apps = [
         'auth_tests',
         'django.contrib.auth',
@@ -115,7 +120,8 @@ class ProxyModelWithSameAppLabelTests(TestCase):
         proxy_model_content_type = ContentType.objects.get_for_model(Proxy, for_concrete_model=False)
         self.assertEqual(self.default_permission.content_type, self.concrete_content_type)
         self.assertEqual(self.custom_permission.content_type, self.concrete_content_type)
-        update_proxy_permissions.update_proxy_model_permissions(apps, None)
+        with connection.schema_editor() as editor:
+            update_proxy_permissions.update_proxy_model_permissions(apps, editor)
         self.default_permission.refresh_from_db()
         self.custom_permission.refresh_from_db()
         self.assertEqual(self.default_permission.content_type, proxy_model_content_type)
@@ -127,15 +133,17 @@ class ProxyModelWithSameAppLabelTests(TestCase):
         user.user_permissions.add(self.custom_permission)
         for permission in [self.default_permission, self.custom_permission]:
             self.assertTrue(user.has_perm('auth_tests.' + permission.codename))
-        update_proxy_permissions.update_proxy_model_permissions(apps, None)
+        with connection.schema_editor() as editor:
+            update_proxy_permissions.update_proxy_model_permissions(apps, editor)
         # Reload user to purge the _perm_cache.
         user = User._default_manager.get(pk=user.pk)
         for permission in [self.default_permission, self.custom_permission]:
             self.assertTrue(user.has_perm('auth_tests.' + permission.codename))
 
     def test_migrate_backwards(self):
-        update_proxy_permissions.update_proxy_model_permissions(apps, None)
-        update_proxy_permissions.revert_proxy_model_permissions(apps, None)
+        with connection.schema_editor() as editor:
+            update_proxy_permissions.update_proxy_model_permissions(apps, editor)
+            update_proxy_permissions.revert_proxy_model_permissions(apps, editor)
         self.default_permission.refresh_from_db()
         self.assertEqual(self.default_permission.content_type, self.concrete_content_type)
         self.custom_permission.refresh_from_db()
@@ -147,8 +155,9 @@ class ProxyModelWithSameAppLabelTests(TestCase):
         user.user_permissions.add(self.custom_permission)
         for permission in [self.default_permission, self.custom_permission]:
             self.assertTrue(user.has_perm('auth_tests.' + permission.codename))
-        update_proxy_permissions.update_proxy_model_permissions(apps, None)
-        update_proxy_permissions.revert_proxy_model_permissions(apps, None)
+        with connection.schema_editor() as editor:
+            update_proxy_permissions.update_proxy_model_permissions(apps, editor)
+            update_proxy_permissions.revert_proxy_model_permissions(apps, editor)
         # Reload user to purge the _perm_cache.
         user = User._default_manager.get(pk=user.pk)
         for permission in [self.default_permission, self.custom_permission]:
@@ -175,5 +184,36 @@ class ProxyModelWithSameAppLabelTests(TestCase):
             name='May display proxys information',
         )
         with captured_stdout() as stdout:
-            update_proxy_permissions.update_proxy_model_permissions(apps, None)
+            with connection.schema_editor() as editor:
+                update_proxy_permissions.update_proxy_model_permissions(apps, editor)
         self.assertIn('A problem arose migrating proxy model permissions', stdout.getvalue())
+
+
+class MultiDBProxyModelAppLabelTests(TransactionTestCase):
+    databases = {'default', 'other'}
+    available_apps = [
+        'auth_tests',
+        'django.contrib.auth',
+        'django.contrib.contenttypes',
+    ]
+
+    def setUp(self):
+        ContentType.objects.all().delete()
+        Permission.objects.using('other').delete()
+        concrete_content_type = ContentType.objects.db_manager(
+            'other'
+        ).get_for_model(Proxy)
+        self.permission = Permission.objects.using('other').create(
+            content_type=concrete_content_type,
+            codename='add_proxy',
+            name='Can add proxy',
+        )
+
+    def test_migrate_other_database(self):
+        proxy_model_content_type = ContentType.objects.db_manager(
+            'other'
+        ).get_for_model(Proxy, for_concrete_model=False)
+        with connections['other'].schema_editor() as editor:
+            update_proxy_permissions.update_proxy_model_permissions(apps, editor)
+        self.permission.refresh_from_db()
+        self.assertEqual(self.permission.content_type, proxy_model_content_type)