[fix] SortedListField: update whole list if order is changed

AUTHORS

@@ -221,3 +221,4 @@ that much better:
  * Michael Chase (https://github.com/rxsegrxup)
  * Eremeev Danil (https://github.com/elephanter)
  * Catstyle Lee (https://github.com/Catstyle)
+ * Kiryl Yermakou (https://github.com/rma4ok)

docs/changelog.rst

@@ -13,6 +13,7 @@ Changes in 0.9.X - DEV
 - Fixed unpickled documents replacing the global field's list. #888
 - Fixed storage of microseconds in ComplexDateTimeField and unused separator option. #910
 - Django support was removed and will be available as a separate extension. #958
+- Fix for updating sorting in SortedListField. #978
 
 Changes in 0.9.0
 ================

mongoengine/base/document.py

@@ -547,6 +547,7 @@ def _get_changed_fields(self, inspected=None):
         EmbeddedDocument = _import_class("EmbeddedDocument")
         DynamicEmbeddedDocument = _import_class("DynamicEmbeddedDocument")
         ReferenceField = _import_class("ReferenceField")
+        SortedListField = _import_class("SortedListField")
         changed_fields = []
         changed_fields += getattr(self, '_changed_fields', [])
 
@@ -577,6 +578,12 @@ def _get_changed_fields(self, inspected=None):
                 if (hasattr(field, 'field') and
                         isinstance(field.field, ReferenceField)):
                     continue
+                elif (isinstance(field, SortedListField) and field._ordering):
+                    # if ordering is affected whole list is changed
+                    if any(map(lambda d: field._ordering in d._changed_fields, data)):
+                        changed_fields.append(db_field_name)
+                        continue
+
                 self._nestable_types_changed_fields(
                     changed_fields, key, data, inspected)
         return changed_fields

tests/fields/fields.py

@@ -916,6 +916,13 @@ class BlogPost(Document):
         self.assertEqual(post.comments[0].content, comment2.content)
         self.assertEqual(post.comments[1].content, comment1.content)
 
+        post.comments[0].order = 2
+        post.save()
+        post.reload()
+
+        self.assertEqual(post.comments[0].content, comment1.content)
+        self.assertEqual(post.comments[1].content, comment2.content)
+
         BlogPost.drop_collection()
 
     def test_reverse_list_sorting(self):