Removed un-needed properties on script tags for JS imports.

Refactored sorting filters from class method into a model property with a default of an empty dictionary.
Refactored sortable admin class to not make two calls to determine sortability and also to get objects for sorting.
Added sorting_filters to sortable admin queryset.

adminsortable/admin.py

@@ -28,6 +28,8 @@ STATIC_URL = settings.STATIC_URL
 
 
 class SortableAdminBase(object):
+    filtered_objects = []
+
     def changelist_view(self, request, extra_context=None):
         """
         If the model that inherits Sortable has more than one object,
@@ -35,12 +37,11 @@ class SortableAdminBase(object):
         object_tools block to take people to the view to change the sorting.
         """
 
-        if self.model.ordering_subset() is not None:
-            objects = self.model.ordering_subset()
-        else:
-            objects = self.queryset(request)
+        # Apply any additional filters to create a subset of sortable objects
+        self.filtered_objects = self.queryset(request).filter(
+            **self.model.sorting_filters)
 
-        if get_is_sortable(objects):
+        if get_is_sortable(self.filtered_objects):
             self.change_list_template = \
                 self.sortable_change_list_with_sort_link_template
             self.is_sortable = True
@@ -66,8 +67,6 @@ class SortableAdmin(SortableAdminBase, ModelAdmin):
         'adminsortable/change_list_with_sort_link.html'
     sortable_change_form_template = 'adminsortable/change_form.html'
     sortable_change_list_template = 'adminsortable/change_list.html'
-    sortable_javascript_includes_template = \
-        'adminsortable/shared/javascript_includes.html'
 
     change_form_template_extends = 'admin/change_form.html'
     change_list_template_extends = 'admin/change_list.html'
@@ -107,10 +106,7 @@ class SortableAdmin(SortableAdminBase, ModelAdmin):
         has_perm = request.user.has_perm('{}.{}'.format(opts.app_label,
             opts.get_change_permission()))
 
-        if self.model.ordering_subset() is not None:
-            objects = self.model.ordering_subset()
-        else:
-            objects = self.queryset(request)
+        objects = self.filtered_objects
 
         # Determine if we need to regroup objects relative to a
         # foreign key specified on the model class that is extending Sortable.
@@ -169,9 +165,7 @@ class SortableAdmin(SortableAdminBase, ModelAdmin):
             'group_expression': sortable_by_expression,
             'sortable_by_class': sortable_by_class,
             'sortable_by_class_is_sortable': sortable_by_class_is_sortable,
-            'sortable_by_class_display_name': sortable_by_class_display_name,
-            'sortable_javascript_includes_template':
-            self.sortable_javascript_includes_template
+            'sortable_by_class_display_name': sortable_by_class_display_name
         }
         return render(request, self.sortable_change_list_template, context)
 
@@ -208,8 +202,6 @@ class SortableAdmin(SortableAdminBase, ModelAdmin):
             self.change_form_template = self.sortable_change_form_template
 
             extra_context.update({
-                'sortable_javascript_includes_template':
-                self.sortable_javascript_includes_template,
                 'has_sortable_tabular_inlines':
                 self.has_sortable_tabular_inlines,
                 'has_sortable_stacked_inlines':

adminsortable/models.py

@@ -31,6 +31,7 @@ class Sortable(models.Model):
     order = models.PositiveIntegerField(editable=False, default=1,
         db_index=True)
     is_sortable = False
+    sorting_filters = {}
 
     # legacy support
     sortable_by = None
@@ -43,10 +44,6 @@ class Sortable(models.Model):
     def model_type_id(cls):
         return ContentType.objects.get_for_model(cls).id
 
-    @classmethod
-    def ordering_subset(cls):
-        return None
-
     def __init__(self, *args, **kwargs):
         super(Sortable, self).__init__(*args, **kwargs)
 

adminsortable/templates/adminsortable/change_list.html

@@ -9,11 +9,11 @@
 
 {% block extrahead %}
 	{{ block.super }}
-    <script type="text/javascript" src="{% static 'admin/js/jquery.js' %}"></script>
-    <script type="text/javascript" src="{% static 'admin/js/jquery.init.js' %}"></script>
-	<script type="text/javascript" src="{% static 'adminsortable/js/jquery-ui-django-admin.min.js' %}"></script>
-    <script type="text/javascript" src="{% static 'adminsortable/js/jquery.django-csrf.js' %}"></script>
-    <script type="text/javascript" src="{% static 'adminsortable/js/admin.sortable.js' %}"></script>
+    <script src="{% static 'admin/js/jquery.js' %}"></script>
+    <script src="{% static 'admin/js/jquery.init.js' %}"></script>
+	<script src="{% static 'adminsortable/js/jquery-ui-django-admin.min.js' %}"></script>
+    <script src="{% static 'adminsortable/js/jquery.django-csrf.js' %}"></script>
+    <script src="{% static 'adminsortable/js/admin.sortable.js' %}"></script>
 {% endblock %}
 
 {% block title %}{% blocktrans with opts.verbose_name_plural|capfirst as model %}Drag and drop {{ model }} to change display order{% endblocktrans %} | {% trans 'Django site admin' %}{% endblock %}

adminsortable/utils.py

@@ -1,4 +1,5 @@
 def get_is_sortable(objects):
-    if objects.count() > 1:
-        return True
+    if objects:
+        if objects.count() > 1:
+            return True
     return False