Refactored out RedirectURLMixin.get_success_url().

This also adds a default implementation of get_default_redirect_url().

django/contrib/auth/views.py

@@ -35,9 +35,13 @@ UserModel = get_user_model()
 
 
 class RedirectURLMixin:
+    next_page = None
     redirect_field_name = REDIRECT_FIELD_NAME
     success_url_allowed_hosts = set()
 
+    def get_success_url(self):
+        return self.get_redirect_url() or self.get_default_redirect_url()
+
     def get_redirect_url(self):
         """Return the user-originating redirect URL if it's safe."""
         redirect_to = self.request.POST.get(
@@ -53,6 +57,12 @@ class RedirectURLMixin:
     def get_success_url_allowed_hosts(self):
         return {self.request.get_host(), *self.success_url_allowed_hosts}
 
+    def get_default_redirect_url(self):
+        """Return the default redirect URL."""
+        if self.next_page:
+            return resolve_url(self.next_page)
+        raise ImproperlyConfigured("No URL to redirect to. Provide a next_page.")
+
 
 class LoginView(RedirectURLMixin, FormView):
     """
@@ -61,7 +71,6 @@ class LoginView(RedirectURLMixin, FormView):
 
     form_class = AuthenticationForm
     authentication_form = None
-    next_page = None
     template_name = "registration/login.html"
     redirect_authenticated_user = False
     extra_context = None
@@ -80,9 +89,6 @@ class LoginView(RedirectURLMixin, FormView):
             return HttpResponseRedirect(redirect_to)
         return super().dispatch(request, *args, **kwargs)
 
-    def get_success_url(self):
-        return self.get_redirect_url() or self.get_default_redirect_url()
-
     def get_default_redirect_url(self):
         """Return the default redirect URL."""
         if self.next_page:
@@ -125,7 +131,6 @@ class LogoutView(RedirectURLMixin, TemplateView):
     # RemovedInDjango50Warning: when the deprecation ends, remove "get" and
     # "head" from http_method_names.
     http_method_names = ["get", "head", "post", "options"]
-    next_page = None
     template_name = "registration/logged_out.html"
     extra_context = None
 
@@ -163,9 +168,6 @@ class LogoutView(RedirectURLMixin, TemplateView):
         else:
             return self.request.path
 
-    def get_success_url(self):
-        return self.get_redirect_url() or self.get_default_redirect_url()
-
     def get_context_data(self, **kwargs):
         context = super().get_context_data(**kwargs)
         current_site = get_current_site(self.request)

tests/auth_tests/test_views.py

@@ -18,6 +18,7 @@ from django.contrib.auth.models import Permission, User
 from django.contrib.auth.views import (
     INTERNAL_RESET_SESSION_TOKEN,
     LoginView,
+    RedirectURLMixin,
     logout_then_login,
     redirect_to_login,
 )
@@ -40,6 +41,20 @@ from .models import CustomUser, UUIDUser
 from .settings import AUTH_TEMPLATES
 
 
+class RedirectURLMixinTests(TestCase):
+    @override_settings(ROOT_URLCONF="auth_tests.urls")
+    def test_get_default_redirect_url_next_page(self):
+        class RedirectURLView(RedirectURLMixin):
+            next_page = "/custom/"
+
+        self.assertEqual(RedirectURLView().get_default_redirect_url(), "/custom/")
+
+    def test_get_default_redirect_url_no_next_page(self):
+        msg = "No URL to redirect to. Provide a next_page."
+        with self.assertRaisesMessage(ImproperlyConfigured, msg):
+            RedirectURLMixin().get_default_redirect_url()
+
+
 @override_settings(
     LANGUAGES=[("en", "English")],
     LANGUAGE_CODE="en",