Fixed #36717 -- Redirect authenticated users on admin login view to next URL.

Co-authored-by: Natalia <124304+nessita@users.noreply.github.com>

2 files changed, 24 insertions, 18 deletions

diff --git a/django/contrib/admin/sites.py b/django/contrib/admin/sites.py
index 17af19fd1b..410bf20da0 100644
--- a/django/contrib/admin/sites.py
+++ b/django/contrib/admin/sites.py
@@ -416,29 +416,27 @@ class AdminSite:
         """
         Display the login form for the given HttpRequest.
         """
-        if request.method == "GET" and self.has_permission(request):
-            # Already logged-in, redirect to admin index
-            index_path = reverse("admin:index", current_app=self.name)
-            return HttpResponseRedirect(index_path)
-
         # Since this module gets imported in the application's root package,
         # it cannot import models from other applications at the module level,
         # and django.contrib.admin.forms eventually imports User.
         from django.contrib.admin.forms import AdminAuthenticationForm
         from django.contrib.auth.views import LoginView
 
+        redirect_url = LoginView().get_redirect_url(request) or reverse(
+            "admin:index", current_app=self.name
+        )
+        if request.method == "GET" and self.has_permission(request):
+            # Already logged-in, redirect accordingly.
+            return HttpResponseRedirect(redirect_url)
+
         context = {
             **self.each_context(request),
             "title": _("Log in"),
             "subtitle": None,
             "app_path": request.get_full_path(),
             "username": request.user.get_username(),
+            REDIRECT_FIELD_NAME: redirect_url,
         }
-        if (
-            REDIRECT_FIELD_NAME not in request.GET
-            and REDIRECT_FIELD_NAME not in request.POST
-        ):
-            context[REDIRECT_FIELD_NAME] = reverse("admin:index", current_app=self.name)
         context.update(extra_context or {})
 
         defaults = {
diff --git a/django/contrib/auth/views.py b/django/contrib/auth/views.py
index 295f2219cf..dcffb4aca6 100644
--- a/django/contrib/auth/views.py
+++ b/django/contrib/auth/views.py
@@ -40,20 +40,28 @@ class RedirectURLMixin:
     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(
-            self.redirect_field_name, self.request.GET.get(self.redirect_field_name)
+    def get_redirect_url(self, request=None):
+        """Return the user-originating redirect URL if it's safe.
+
+        Optionally takes a request argument, allowing use outside class-based
+        views.
+        """
+        if request is None:
+            request = self.request
+        redirect_to = request.POST.get(
+            self.redirect_field_name, request.GET.get(self.redirect_field_name)
         )
         url_is_safe = url_has_allowed_host_and_scheme(
             url=redirect_to,
-            allowed_hosts=self.get_success_url_allowed_hosts(),
-            require_https=self.request.is_secure(),
+            allowed_hosts=self.get_success_url_allowed_hosts(request),
+            require_https=request.is_secure(),
         )
         return redirect_to if url_is_safe else ""
 
-    def get_success_url_allowed_hosts(self):
-        return {self.request.get_host(), *self.success_url_allowed_hosts}
+    def get_success_url_allowed_hosts(self, request=None):
+        if request is None:
+            request = self.request
+        return {request.get_host(), *self.success_url_allowed_hosts}
 
     def get_default_redirect_url(self):
         """Return the default redirect URL."""