From d593f7e04b6bf26b576b597b2a68dfd72b400269 Mon Sep 17 00:00:00 2001
From: Ross Lawley <ross.lawley@gmail.com>
Date: Thu, 11 Jul 2013 08:11:00 +0000
Subject: [PATCH] Fixed EmbeddedDocuments with `id` also storing `_id` (#402)

---
 mongoengine/base/document.py | 6 ++++--
 tests/document/instance.py   | 7 +++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/mongoengine/base/document.py b/mongoengine/base/document.py
index cbce4ffe..536fc2f4 100644
--- a/mongoengine/base/document.py
+++ b/mongoengine/base/document.py
@@ -262,8 +262,10 @@ class BaseDocument(object):
                 data[field.db_field] = value
 
         # If "_id" has not been set, then try and set it
-        if data["_id"] is None:
-            data["_id"] = self._data.get("id", None)
+        Document = _import_class("Document")
+        if isinstance(self, Document):
+            if data["_id"] is None:
+                data["_id"] = self._data.get("id", None)
 
         if data['_id'] is None:
             data.pop('_id')
diff --git a/tests/document/instance.py b/tests/document/instance.py
index e85c9d86..a61c4396 100644
--- a/tests/document/instance.py
+++ b/tests/document/instance.py
@@ -444,6 +444,13 @@ class InstanceTest(unittest.TestCase):
         self.assertEqual(Employee(name="Bob", age=35, salary=0).to_mongo().keys(),
                          ['_cls', 'name', 'age', 'salary'])
 
+    def test_embedded_document_to_mongo_id(self):
+        class SubDoc(EmbeddedDocument):
+            id = StringField(required=True)
+
+        sub_doc = SubDoc(id="abc")
+        self.assertEqual(sub_doc.to_mongo().keys(), ['id'])
+
     def test_embedded_document(self):
         """Ensure that embedded documents are set up correctly.
         """