Fixed Django 4.0 compatibility using django-upgrade

example/example/urls.py

@@ -1,11 +1,11 @@
-from django.conf.urls import include, url
+from django.urls import include, path
 from django.contrib import admin
 from django.urls import reverse_lazy
 from django.views.generic import RedirectView
 
 admin.autodiscover()
 
 urlpatterns = [
-    url(r"^admin/", admin.site.urls),
-    url(r"^$", RedirectView.as_view(url=reverse_lazy("admin:index"), permanent=False)),
+    path('admin/', admin.site.urls),
+    path('', RedirectView.as_view(url=reverse_lazy("admin:index"), permanent=False)),
 ]

example/orders/models.py

@@ -1,6 +1,6 @@
 from django.db import models
 from django.utils.dates import MONTHS_3
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 
 from polymorphic.models import PolymorphicModel
 

polymorphic/tests/admintestcase.py

@@ -1,5 +1,5 @@
 from django.conf import settings
-from django.conf.urls import include, url
+from django.urls import include, path
 from django.contrib.admin import AdminSite
 from django.contrib.admin.templatetags.admin_urls import admin_urlname
 from django.contrib.auth.models import User
@@ -53,7 +53,7 @@ def admin_register(self, model, admin_site):
 
         # Make sure the URLs are reachable by reverse()
         clear_url_caches()
-        set_urlconf(tuple([url("^tmp-admin/", self.admin_site.urls)]))
+        set_urlconf(tuple([path('tmp-admin/', self.admin_site.urls)]))
 
     def get_admin_instance(self, model):
         try:

runtests.py

@@ -32,6 +32,7 @@
                 env="SECONDARY_DATABASE", default="sqlite://:memory:"
             ),
         },
+        DEFAULT_AUTO_FIELD="django.db.models.AutoField",
         TEST_RUNNER="django.test.runner.DiscoverRunner",
         INSTALLED_APPS=(
             "django.contrib.auth",