Login: Fix error page when invalid username/password

Author: marlonkeating

democracylab/views.py

@@ -24,18 +24,21 @@ def login_view(request, provider=None):
         email = request.POST['username']
         password = request.POST['password']
         prev_page = request.POST['prevPage']
-        prev_page_args = {}
+        prev_page_args_string = None
         if 'prevPageArgs' in request.POST and len(request.POST['prevPageArgs']) > 0:
             prev_page_args_string = request.POST['prevPageArgs'].strip('\'\"').replace('\\', '')
-            prev_page_args = json.loads(prev_page_args_string)
         user = authenticate(username=email.lower(), password=password)
         if user is not None and user.is_authenticated:
             login(request, user)
+            prev_page_args = json.loads(prev_page_args_string) if prev_page_args_string else None
             redirect_url = '/' if prev_page.strip('/') == '' else section_url(prev_page, prev_page_args)
             return redirect(redirect_url)
         else:
             messages.error(request, 'Incorrect Email or Password')
-            return redirect(section_url(FrontEndSection.LogIn, {'prev': prev_page, 'prevPageArgs': prev_page_args_string}))
+            back_args = {'prev': prev_page}
+            if prev_page_args_string:
+                back_args['prevPageArgs'] = prev_page_args_string
+            return redirect(section_url(FrontEndSection.LogIn, back_args))
 
     if provider in provider_ids:
         return redirect(f'{provider}_login')