Merge pull request #209 from stephrdev/improve-querystring-filter

Improve querystring filtering.

adminsortable/admin.py

@@ -6,6 +6,7 @@ from django.conf import settings
 from django.conf.urls import url
 from django.contrib.admin import ModelAdmin, TabularInline, StackedInline
 from django.contrib.admin.options import InlineModelAdmin
+from django.contrib.admin.views.main import IGNORED_PARAMS
 from django.contrib.contenttypes.admin import (GenericStackedInline,
                                                GenericTabularInline)
 from django.contrib.contenttypes.models import ContentType
@@ -38,8 +39,8 @@ class SortableAdminBase(object):
         filters = {}
 
         for k, v in request.GET.items():
-            if k not in ['_to_field', '_popup',]:
-                filters.update({ k: v })
+            if k not in IGNORED_PARAMS:
+                filters[k] = v
 
         return filters