added a feature to save object data in order

mongoengine/dereference.py

@@ -1,3 +1,4 @@
+from collections import OrderedDict
 from bson import DBRef, SON
 import six
 
@@ -201,6 +202,10 @@ def _attach_objects(self, items, depth=0, instance=None, name=None):
             as_tuple = isinstance(items, tuple)
             iterator = enumerate(items)
             data = []
+        elif isinstance(items, OrderedDict):
+            is_list = False
+            iterator = items.iteritems()
+            data = OrderedDict()
         else:
             is_list = False
             iterator = items.iteritems()

mongoengine/fields.py

@@ -5,6 +5,7 @@
 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 @@ def to_mongo(self, value, use_db_field=True, fields=None):
             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)
 

tests/fields/fields.py

@@ -5,8 +5,10 @@
 import math
 import itertools
 import re
+import pymongo
 
 from nose.plugins.skip import SkipTest
+from collections import OrderedDict
 import six
 
 try:
@@ -25,9 +27,12 @@
 from mongoengine import *
 from mongoengine.connection import get_db
 from mongoengine.base import (BaseDict, BaseField, EmbeddedDocumentList,
-                              _document_registry)
+                              _document_registry, TopLevelDocumentMetaclass)
 
-from tests.utils import MongoDBTestCase
+from tests.utils import MongoDBTestCase, MONGO_TEST_DB
+from mongoengine.python_support import IS_PYMONGO_3
+if IS_PYMONGO_3:
+    from bson import CodecOptions
 
 __all__ = ("FieldTest", "EmbeddedDocumentListFieldTestCase")
 
@@ -4499,6 +4504,67 @@ class CustomData(Document):
         self.assertTrue(hasattr(CustomData.c_field, 'custom_data'))
         self.assertEqual(custom_data['a'], CustomData.c_field.custom_data['a'])
 
+    def test_dynamicfield_with_container_class(self):
+        """
+        Tests that object can be stored in order by DynamicField class
+        with container_class parameter.
+        """
+        raw_data = [('d', 1), ('c', 2), ('b', 3), ('a', 4)]
+
+        class Doc(Document):
+            ordered_data = DynamicField(container_class=OrderedDict)
+            unordered_data = DynamicField()
+
+        Doc.drop_collection()
+
+        doc = Doc(ordered_data=OrderedDict(raw_data), unordered_data=dict(raw_data)).save()
+
+        # checks that the data is in order
+        self.assertEqual(type(doc.ordered_data), OrderedDict)
+        self.assertEqual(type(doc.unordered_data), dict)
+        self.assertEqual(','.join(doc.ordered_data.keys()), 'd,c,b,a')
+
+        # checks that the data is stored to the database in order
+        pymongo_db = pymongo.MongoClient()[MONGO_TEST_DB]
+        if IS_PYMONGO_3:
+            codec_option = CodecOptions(document_class=OrderedDict)
+            db_doc = pymongo_db.doc.with_options(codec_options=codec_option).find_one()
+        else:
+            db_doc = pymongo_db.doc.find_one(as_class=OrderedDict)
+
+        self.assertEqual(','.join(doc.ordered_data.keys()), 'd,c,b,a')
+
+    def test_dynamicfield_with_wrong_container_class(self):
+        with self.assertRaises(ValidationError):
+            class DocWithInvalidField:
+                data = DynamicField(container_class=list)
+
+    def test_dynamicfield_with_wrong_container_class_and_reload_docuemnt(self):
+        # This is because 'codec_options' is supported on pymongo3 or later
+        if IS_PYMONGO_3:
+            class OrderedDocument(Document):
+                my_metaclass = TopLevelDocumentMetaclass
+                __metaclass__ = TopLevelDocumentMetaclass
+
+                @classmethod
+                def _get_collection(cls):
+                    collection = super(OrderedDocument, cls)._get_collection()
+                    opts = CodecOptions(document_class=OrderedDict)
+
+                    return collection.with_options(codec_options=opts)
+
+            raw_data = [('d', 1), ('c', 2), ('b', 3), ('a', 4)]
+
+            class Doc(OrderedDocument):
+                data = DynamicField(container_class=OrderedDict)
+
+            Doc.drop_collection()
+
+            doc = Doc(data=OrderedDict(raw_data)).save()
+            doc.reload()
+
+            self.assertEqual(type(doc.data), OrderedDict)
+            self.assertEqual(','.join(doc.data.keys()), 'd,c,b,a')
 
 if __name__ == '__main__':
     unittest.main()

tests/test_dereference.py

@@ -2,10 +2,15 @@
 import unittest
 
 from bson import DBRef, ObjectId
+from collections import OrderedDict
 
 from mongoengine import *
 from mongoengine.connection import get_db
 from mongoengine.context_managers import query_counter
+from mongoengine.python_support import IS_PYMONGO_3
+from mongoengine.base import TopLevelDocumentMetaclass
+if IS_PYMONGO_3:
+    from bson import CodecOptions
 
 
 class FieldTest(unittest.TestCase):
@@ -1287,5 +1292,70 @@ class Playlist(Document):
 
             self.assertEqual(q, 2)
 
+    def test_dynamic_field_dereference(self):
+        class Merchandise(Document):
+            name = StringField()
+            price = IntField()
+
+        class Store(Document):
+            merchandises = DynamicField()
+
+        Merchandise.drop_collection()
+        Store.drop_collection()
+
+        merchandises = {
+            '#1': Merchandise(name='foo', price=100).save(),
+            '#2': Merchandise(name='bar', price=120).save(),
+            '#3': Merchandise(name='baz', price=110).save(),
+        }
+        Store(merchandises=merchandises).save()
+
+        store = Store.objects().first()
+        for obj in store.merchandises.values():
+            self.assertFalse(isinstance(obj, Merchandise))
+
+        store.select_related()
+        for obj in store.merchandises.values():
+            self.assertTrue(isinstance(obj, Merchandise))
+
+    def test_dynamic_field_dereference_with_ordering_guarantee_on_pymongo3(self):
+        # This is because 'codec_options' is supported on pymongo3 or later
+        if IS_PYMONGO_3:
+            class OrderedDocument(Document):
+                my_metaclass = TopLevelDocumentMetaclass
+                __metaclass__ = TopLevelDocumentMetaclass
+
+                @classmethod
+                def _get_collection(cls):
+                    collection = super(OrderedDocument, cls)._get_collection()
+                    opts = CodecOptions(document_class=OrderedDict)
+
+                    return collection.with_options(codec_options=opts)
+
+            class Merchandise(Document):
+                name = StringField()
+                price = IntField()
+
+            class Store(OrderedDocument):
+                merchandises = DynamicField(container_class=OrderedDict)
+
+            Merchandise.drop_collection()
+            Store.drop_collection()
+
+            merchandises = OrderedDict()
+            merchandises['#1'] = Merchandise(name='foo', price=100).save()
+            merchandises['#2'] = Merchandise(name='bar', price=120).save()
+            merchandises['#3'] = Merchandise(name='baz', price=110).save()
+
+            Store(merchandises=merchandises).save()
+
+            store = Store.objects().first()
+
+            store.select_related()
+
+            # confirms that the load data order is same with the one at storing
+            self.assertTrue(type(store.merchandises), OrderedDict)
+            self.assertEqual(','.join(store.merchandises.keys()), '#1,#2,#3')
+
 if __name__ == '__main__':
     unittest.main()