Added properties to allow sortable change list and change form view to extend a custom template or extend the default admin change form and change list templates.

Fixed a problem with the detection of sortability of inline models at the template level that was preventing the drag-and-drop messaging in the template to be displayed.
Updated unit tests.

adminsortable/admin.py

@@ -40,6 +40,13 @@ class SortableAdminBase(object):
             self.change_list_template = \
                 self.sortable_change_list_with_sort_link_template
             self.is_sortable = True
+
+        if extra_context is None:
+            extra_context = {}
+
+        extra_context.update({
+            'change_list_template_extends': self.change_list_template_extends
+        })
         return super(SortableAdminBase, self).changelist_view(request,
             extra_context=extra_context)
 
@@ -58,6 +65,9 @@ class SortableAdmin(SortableAdminBase, ModelAdmin):
     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'
+
     class Meta:
         abstract = True
 
@@ -162,6 +172,13 @@ class SortableAdmin(SortableAdminBase, ModelAdmin):
         self.has_sortable_tabular_inlines = False
         self.has_sortable_stacked_inlines = False
 
+        if extra_context is None:
+            extra_context = {}
+
+        extra_context.update({
+            'change_form_template_extends': self.change_form_template_extends
+        })
+
         for klass in self.inlines:
             is_sortable = klass.model.is_sortable
             if issubclass(klass, SortableTabularInline) and is_sortable:
@@ -171,15 +188,18 @@ class SortableAdmin(SortableAdminBase, ModelAdmin):
 
         if self.has_sortable_tabular_inlines or \
                 self.has_sortable_stacked_inlines:
+
             self.change_form_template = self.sortable_change_form_template
-            extra_context = {
+
+            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':
                 self.has_sortable_stacked_inlines
-            }
+            })
+
         return super(SortableAdmin, self).change_view(request, object_id,
             extra_context=extra_context)
 
@@ -238,21 +258,21 @@ class SortableInlineBase(SortableAdminBase, InlineModelAdmin):
         return qs
 
 
-class SortableTabularInline(SortableInlineBase, TabularInline):
+class SortableTabularInline(TabularInline, SortableInlineBase):
     """Custom template that enables sorting for tabular inlines"""
     template = 'adminsortable/edit_inline/tabular.html'
 
 
-class SortableStackedInline(SortableInlineBase, StackedInline):
+class SortableStackedInline(StackedInline, SortableInlineBase):
     """Custom template that enables sorting for stacked inlines"""
     template = 'adminsortable/edit_inline/stacked.html'
 
 
-class SortableGenericTabularInline(SortableInlineBase, GenericTabularInline):
+class SortableGenericTabularInline(GenericTabularInline, SortableInlineBase):
     """Custom template that enables sorting for tabular inlines"""
     template = 'adminsortable/edit_inline/tabular.html'
 
 
-class SortableGenericStackedInline(SortableInlineBase, GenericStackedInline):
+class SortableGenericStackedInline(GenericStackedInline, SortableInlineBase):
     """Custom template that enables sorting for stacked inlines"""
     template = 'adminsortable/edit_inline/stacked.html'

adminsortable/models.py

@@ -39,19 +39,6 @@ class Sortable(models.Model):
         abstract = True
         ordering = ['order']
 
-    # @classmethod
-    # def determine_if_sortable(cls):
-    #     try:
-    #         max_order = cls.objects.aggregate(
-    #             models.Max('order'))['order__max']
-    #     except (TypeError, IndexError):
-    #         max_order = 0
-
-    #     if max_order > 1:
-    #         cls.is_sortable = True
-    #     else:
-    #         cls.is_sortable = False
-
     @classmethod
     def model_type_id(cls):
         return ContentType.objects.get_for_model(cls).id

adminsortable/templates/adminsortable/change_form.html

@@ -1,4 +1,4 @@
-{% extends "admin/change_form.html" %}
+{% extends change_form_template_extends %}
 {% load i18n admin_modify %}
 {% load url from future %}
 

adminsortable/templates/adminsortable/change_list_with_sort_link.html

@@ -1,4 +1,4 @@
-{% extends 'admin/change_list.html' %}
+{% extends change_list_template_extends %}
 {% load i18n %}
 
 {% block object-tools-items %}
@@ -6,4 +6,4 @@
 		<a href="./sort/">{% trans 'Change Order' %}</a>
 	</li>
 	{{ block.super }}
-{% endblock %}
+{% endblock %}

adminsortable/templates/adminsortable/edit_inline/stacked.html

@@ -1,6 +1,6 @@
 {% load i18n admin_modify adminsortable_tags %}
 <div class="inline-group" id="{{ inline_admin_formset.formset.prefix }}-group">
-  <h2>{{ inline_admin_formset.opts.verbose_name_plural|title }} {% if inline_admin_formset.opts.is_sortable %} - drag and drop to change order{% endif %}</h2>
+  <h2>{{ inline_admin_formset.opts.verbose_name_plural|title }} {% if inline_admin_formset.formset.initial_form_count > 1 %} - drag and drop to change order{% endif %}</h2>
 {{ inline_admin_formset.formset.management_form }}
 {{ inline_admin_formset.formset.non_form_errors }}
 

adminsortable/templates/adminsortable/edit_inline/tabular.html

@@ -3,7 +3,7 @@
   <div class="tabular inline-related {% if forloop.last %}last-related{% endif %}">
 {{ inline_admin_formset.formset.management_form }}
 <fieldset class="module">
-   <h2>{{ inline_admin_formset.opts.verbose_name_plural|capfirst }} {% if inline_admin_formset.opts.is_sortable %} - drag and drop to change order{% endif %}</h2>
+   <h2>{{ inline_admin_formset.opts.verbose_name_plural|capfirst }} {% if inline_admin_formset.formset.initial_form_count > 1 %} - drag and drop to change order{% endif %}</h2>
    {{ inline_admin_formset.formset.non_form_errors }}
    <table>
      <thead><tr>