Merge pull request #1497 from userlocalhost/feature/order_guarantee

added a feature to save object data in order

mongoengine/fields.py

@@ -5,6 +5,7 @@ import re
 import time
 import uuid
 import warnings
+from collections import Mapping
 from operator import itemgetter
 
 from bson import Binary, DBRef, ObjectId, SON
@@ -619,6 +620,14 @@ class DynamicField(BaseField):
 
     Used by :class:`~mongoengine.DynamicDocument` to handle dynamic data"""
 
+    def __init__(self, container_class=dict, *args, **kwargs):
+        self._container_cls = container_class
+        if not issubclass(self._container_cls, Mapping):
+            self.error('The class that is specified in `container_class` parameter '
+                       'must be a subclass of `dict`.')
+
+        super(DynamicField, self).__init__(*args, **kwargs)
+
     def to_mongo(self, value, use_db_field=True, fields=None):
         """Convert a Python type to a MongoDB compatible type.
         """
@@ -644,7 +653,7 @@ class DynamicField(BaseField):
             is_list = True
             value = {k: v for k, v in enumerate(value)}
 
-        data = {}
+        data = self._container_cls()
         for k, v in value.iteritems():
             data[k] = self.to_mongo(v, use_db_field, fields)