From a8bfb5007ed13b586367f7473d5e35eca3befa99 Mon Sep 17 00:00:00 2001
From: Diederik van der Boor <vdboor@edoburu.nl>
Date: Thu, 6 Apr 2017 14:11:56 +0200
Subject: [PATCH] Fix TypeError on Python 3 when querystring is preserved in
 the admin.

Fixes: #263
---
 polymorphic/admin/parentadmin.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/polymorphic/admin/parentadmin.py b/polymorphic/admin/parentadmin.py
index 744ac28..0169225 100644
--- a/polymorphic/admin/parentadmin.py
+++ b/polymorphic/admin/parentadmin.py
@@ -359,7 +359,9 @@ class PolymorphicParentModelAdmin(admin.ModelAdmin):
 
         extra_qs = ''
         if request.META['QUERY_STRING']:
-            extra_qs = '&' + request.META['QUERY_STRING']
+            # QUERY_STRING is bytes in Python 3, using force_text() to decode it as string.
+            # See QueryDict how Django deals with that.
+            extra_qs = '&{0}'.format(force_text(request.META['QUERY_STRING']))
 
         choices = self.get_child_type_choices(request, 'add')
         if len(choices) == 1: