Fixed #28229 -- Fixed the value of LoginView's "next" template variable.

django/contrib/auth/views.py

@@ -65,7 +65,11 @@ class LoginView(SuccessURLAllowedHostsMixin, FormView):
         return super().dispatch(request, *args, **kwargs)
 
     def get_success_url(self):
-        """Ensure the user-originating redirection URL is safe."""
+        url = self.get_redirect_url()
+        return url or resolve_url(settings.LOGIN_REDIRECT_URL)
+
+    def get_redirect_url(self):
+        """Return the user-originating redirect URL if it's safe."""
         redirect_to = self.request.POST.get(
             self.redirect_field_name,
             self.request.GET.get(self.redirect_field_name, '')
@@ -75,9 +79,7 @@ class LoginView(SuccessURLAllowedHostsMixin, FormView):
             allowed_hosts=self.get_success_url_allowed_hosts(),
             require_https=self.request.is_secure(),
         )
-        if not url_is_safe:
-            return resolve_url(settings.LOGIN_REDIRECT_URL)
-        return redirect_to
+        return redirect_to if url_is_safe else ''
 
     def get_form_class(self):
         return self.authentication_form or self.form_class
@@ -96,7 +98,7 @@ class LoginView(SuccessURLAllowedHostsMixin, FormView):
         context = super().get_context_data(**kwargs)
         current_site = get_current_site(self.request)
         context.update({
-            self.redirect_field_name: self.get_success_url(),
+            self.redirect_field_name: self.get_redirect_url(),
             'site': current_site,
             'site_name': current_site.name,
         })

docs/releases/1.11.3.txt

@@ -35,3 +35,8 @@ Bugfixes
 
 * Prevented ``Paginator``’s unordered object list warning from evaluating a
   ``QuerySet`` (:ticket:`28284`).
+
+* Fixed the value of ``redirect_field_name`` in ``LoginView``’s template
+  context. It's now an empty string (as it is for the original function-based
+  ``login()`` view) if the corresponding parameter isn't sent in a request (in
+  particular, when the login page is accessed directly) (:ticket:`28229`).

tests/auth_tests/test_views.py

@@ -835,6 +835,7 @@ class LoginRedirectAuthenticatedUser(AuthViewsTestCase):
         self.login()
         response = self.client.get(self.dont_redirect_url)
         self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.context['next'], '')
 
     def test_guest(self):
         """If not logged in, stay on the same page."""