Using "id" in data not "_id" as its a mapping of fieldnames (#255)

docs/changelog.rst

@@ -10,7 +10,7 @@ Changes in 0.7.10
 - Added Django sessions TTL support (#224)
 - Fixed issue with numerical keys in MapField(EmbeddedDocumentField()) (#240)
 - Fixed clearing _changed_fields for complex nested embedded documents (#237, #239, #242)
-- Added "_id" to _data dictionary (#255)
+- Added "id" back to _data dictionary (#255)
 - Only mark a field as changed if the value has changed (#258)
 - Explicitly check for Document instances when dereferencing (#261)
 - Fixed order_by chaining issue (#265)

mongoengine/base.py

@@ -192,7 +192,7 @@ class BaseField(object):
             return self
 
         # Get value from document instance if available, if not use default
-        value = instance._data.get(self.name or self.db_field)
+        value = instance._data.get(self.name)
 
         if value is None:
             value = self.default
@@ -207,9 +207,9 @@ class BaseField(object):
         """
         changed = False
         if (self.name not in instance._data or
-           instance._data[self.name or self.db_field] != value):
+           instance._data[self.name] != value):
             changed = True
-            instance._data[self.name or self.db_field] = value
+            instance._data[self.name] = value
         if changed and instance._initialised:
             instance._mark_as_changed(self.name)
 
@@ -825,6 +825,7 @@ class TopLevelDocumentMetaclass(DocumentMetaclass):
         if not new_class._meta.get('id_field'):
             new_class._meta['id_field'] = 'id'
             new_class._fields['id'] = ObjectIdField(db_field='_id')
+            new_class._fields['id'].name = 'id'
             new_class.id = new_class._fields['id']
 
         # Merge in exceptions with parent hierarchy

tests/test_document.py

@@ -1553,8 +1553,8 @@ class DocumentTest(unittest.TestCase):
         self.assertEqual(2, len(keys))
         self.assertTrue('e' in keys)
         # Ensure that the _id field has the right id
-        self.assertTrue('_id' in keys)
-        self.assertEqual(doc._data.get('_id'), doc.id)
+        self.assertTrue('id' in keys)
+        self.assertEqual(doc._data.get('id'), doc.id)
 
     def test_save(self):
         """Ensure that a document may be saved in the database.
@@ -3402,8 +3402,8 @@ class DocumentTest(unittest.TestCase):
         Person(name="Harry Potter").save()
 
         person = Person.objects.first()
-        self.assertTrue('_id' in person._data.keys())
-        self.assertEqual(person._data.get('_id'), person.id)
+        self.assertTrue('id' in person._data.keys())
+        self.assertEqual(person._data.get('id'), person.id)
 
     def test_complex_nesting_document_and_embedded_document(self):