Added SortableHiddenMixin to copy a useful shortcut from Grappelli

Author: brandenhall

CHANGELOG.rst

@@ -5,9 +5,14 @@ Changelog
 
 * Fixed: visual inconsistencies in grappelli tabular inline styles (`#136`_)
 * Fixed: numerous issues with django-polymorphic integration (`#138`_)
+* Feature: Added ``SortableHiddenMixin`` akin to grappelli’s
+`GrappelliSortableHiddenMixin`_ (`#123`_). Thanks `@brandenhall`_!
 
 .. _#136: https://github.com/theatlantic/django-nested-admin/issues/136
 .. _#138: https://github.com/theatlantic/django-nested-admin/issues/138
+.. _GrappelliSortableHiddenMixin: https://django-grappelli.readthedocs.io/en/2.12.2/customization.html#grappellisortablehiddenmixin
+.. _#123: https://github.com/theatlantic/django-nested-admin/pull/123
+.. @brandenhall_: https://github.com/brandenhall
 
 **3.2.2 (Apr 9, 2019)**
 

docs/customization.rst

@@ -9,6 +9,28 @@ Sortables
 
 The steps for enabling drag-and-drop sorting functionality is identical to Grappelli’s (even with the vanilla Django admin), so the `Grappelli documentation <http://django-grappelli.readthedocs.org/en/latest/customization.html#inline-sortables>`_ for this feature is the best reference. This is equally true of sortables in Django Suit—do not follow Django Suit’s instructions for sortables, as they will not work. The `other features of Grappelli <http://django-grappelli.readthedocs.org/en/latest/customization.html>`_ have not been ported to work with vanilla Django, but in principle they should all still work with nested inlines using django-nested-admin if Grappelli is installed. If you run into any difficulty with this, please `create an issue <https://github.com/theatlantic/django-nested-admin/issues>`_ on this project’s Github.
 
+If you want to have a sortable inline and also want to hide the field you're sorting, you can use  ``SortableHiddenMixin``. Note that this mixin sets ``sortable_field_name`` to ``position`` by default (though this can be overridden by setting ``sortable_field_name`` on your inline class) and must be inherited prior to ``NestedStackedInline`` or ``NestedTabularInline``.
+
+.. code-block:: python
+
+    import nested_admin
+    from django.contrib import admin
+    from .models import TableOfContents, TocArticle, TocSection
+
+    class TocArticleInline(nested_admin.SortableHiddenMixin,
+                           nested_admin.NestedStackedInline):
+        model = TocArticle
+
+    class TocSectionInline(nested_admin.SortableHiddenMixin,
+                           nested_admin.NestedStackedInline):
+        model = TocSection
+        inlines = [TocArticleInline]
+
+    @admin.register(TableOfContents)
+    class TableOfContentsAdmin(nested_admin.NestedModelAdmin):
+        inlines = [TocSectionInline]
+
+
 Events
 ======
 

nested_admin/__init__.py

@@ -22,6 +22,8 @@
 
 # import mapping to objects in other modules
 all_by_module = {
+    'nested_admin.forms': (
+        'SortableHiddenMixin'),
     'nested_admin.formsets': (
         'NestedInlineFormSet', 'NestedBaseGenericInlineFormSet'),
     'nested_admin.nested': (
@@ -42,7 +44,7 @@
     'NestedGenericStackedPolymorphicInline')
 
 # modules that should be imported when accessed as attributes of nested_admin
-attribute_modules = frozenset(['formsets', 'nested', 'polymorphic'])
+attribute_modules = frozenset(['forms', 'formsets', 'nested', 'polymorphic'])
 
 object_origins = {}
 for module, items in all_by_module.items():

nested_admin/forms.py

@@ -0,0 +1,18 @@
+from django.forms.widgets import HiddenInput
+
+
+class SortableHiddenMixin(object):
+    """
+    Enables inline sorting and hides the sortable field.
+
+    By default it assumes the field name is ``position``. This can be
+    overridden by setting the ``sortable_field_name`` attribute to a
+    different value.
+    """
+    sortable_field_name = "position"
+
+    def formfield_for_dbfield(self, db_field, **kwargs):
+        if db_field.name == self.sortable_field_name:
+            kwargs["widget"] = HiddenInput()
+        return super(SortableHiddenMixin, self).formfield_for_dbfield(
+            db_field, **kwargs)