fix: 配置仅已存在用户登录后 cas用户首次登录报403 (#8752)

Co-authored-by: feng626 <1304903146@qq.com>

apps/authentication/backends/cas/urls.py

@@ -3,9 +3,10 @@
 from django.urls import path
 import django_cas_ng.views
 
+from .views import CASLoginView
 
 urlpatterns = [
-    path('login/', django_cas_ng.views.LoginView.as_view(), name='cas-login'),
+    path('login/', CASLoginView.as_view(), name='cas-login'),
     path('logout/', django_cas_ng.views.LogoutView.as_view(), name='cas-logout'),
     path('callback/', django_cas_ng.views.CallbackView.as_view(), name='cas-proxy-callback'),
 ]

apps/authentication/backends/cas/views.py

@@ -0,0 +1,15 @@
+from django_cas_ng.views import LoginView
+from django.core.exceptions import PermissionDenied
+from django.http import HttpResponseRedirect
+
+__all__ = ['LoginView']
+
+
+class CASLoginView(LoginView):
+    def get(self, request):
+        try:
+            return super().get(request)
+        except PermissionDenied:
+            return HttpResponseRedirect('/')
+
+