Dynamic Fields store and recompose Embedded Documents / Documents correctly (#449)

docs/changelog.rst

@@ -4,6 +4,7 @@ Changelog
 
 Changes in 0.8.4
 ================
+- Dynamic Fields store and recompose Embedded Documents / Documents correctly (#449)
 - Handle dynamic fieldnames that look like digits (#434)
 - Added get_user_document and improve mongo_auth module (#423)
 - Added str representation of GridFSProxy (#424)

mongoengine/fields.py

@@ -624,7 +624,9 @@ class DynamicField(BaseField):
             cls = value.__class__
             val = value.to_mongo()
             # If we its a document thats not inherited add _cls
-            if (isinstance(value, (Document, EmbeddedDocument))):
+            if (isinstance(value, Document)):
+                val = {"_ref": value.to_dbref(), "_cls": cls.__name__}
+            if (isinstance(value, EmbeddedDocument)):
                 val['_cls'] = cls.__name__
             return val
 
@@ -645,6 +647,15 @@ class DynamicField(BaseField):
             value = [v for k, v in sorted(data.iteritems(), key=itemgetter(0))]
         return value
 
+    def to_python(self, value):
+        if isinstance(value, dict) and '_cls' in value:
+            doc_cls = get_document(value['_cls'])
+            if '_ref' in value:
+                value = doc_cls._get_db().dereference(value['_ref'])
+            return doc_cls._from_son(value)
+
+        return super(DynamicField, self).to_python(value)
+
     def lookup_member(self, member_name):
         return member_name
 

tests/fields/fields.py

@@ -2506,5 +2506,46 @@ class FieldTest(unittest.TestCase):
         self.assertTrue(tuple(x.items[0]) in tuples)
         self.assertTrue(x.items[0] in tuples)
 
+    def test_dynamic_fields_class(self):
+
+        class Doc2(Document):
+            field_1 = StringField(db_field='f')
+
+        class Doc(Document):
+            my_id = IntField(required=True, unique=True, primary_key=True)
+            embed_me = DynamicField(db_field='e')
+            field_x = StringField(db_field='x')
+
+        Doc.drop_collection()
+        Doc2.drop_collection()
+
+        doc2 = Doc2(field_1="hello")
+        doc = Doc(my_id=1, embed_me=doc2, field_x="x")
+        self.assertRaises(OperationError, doc.save)
+
+        doc2.save()
+        doc.save()
+
+        doc = Doc.objects.get()
+        self.assertEqual(doc.embed_me.field_1, "hello")
+
+    def test_dynamic_fields_embedded_class(self):
+
+        class Embed(EmbeddedDocument):
+            field_1 = StringField(db_field='f')
+
+        class Doc(Document):
+            my_id = IntField(required=True, unique=True, primary_key=True)
+            embed_me = DynamicField(db_field='e')
+            field_x = StringField(db_field='x')
+
+        Doc.drop_collection()
+
+        Doc(my_id=1, embed_me=Embed(field_1="hello"), field_x="x").save()
+
+        doc = Doc.objects.get()
+        self.assertEqual(doc.embed_me.field_1, "hello")
+
+
 if __name__ == '__main__':
     unittest.main()