Fixed dereference issue with embedded listfield referencefields (#439)

docs/changelog.rst

@@ -4,6 +4,7 @@ Changelog
 
 Changes in 0.8.4
 ================
+- Fixed dereference issue with embedded listfield referencefields (#439)
 - Fixed slice when using inheritance causing fields to be excluded (#437)
 - Fixed ._get_db() attribute after a Document.switch_db() (#441)
 - Dynamic Fields store and recompose Embedded Documents / Documents correctly (#449)

mongoengine/dereference.py

@@ -4,7 +4,7 @@ from base import (BaseDict, BaseList, TopLevelDocumentMetaclass, get_document)
 from fields import (ReferenceField, ListField, DictField, MapField)
 from connection import get_db
 from queryset import QuerySet
-from document import Document
+from document import Document, EmbeddedDocument
 
 
 class DeReference(object):
@@ -33,7 +33,8 @@ class DeReference(object):
         self.max_depth = max_depth
         doc_type = None
 
-        if instance and isinstance(instance, (Document, TopLevelDocumentMetaclass)):
+        if instance and isinstance(instance, (Document, EmbeddedDocument,
+                                              TopLevelDocumentMetaclass)):
             doc_type = instance._fields.get(name)
             if hasattr(doc_type, 'field'):
                 doc_type = doc_type.field

tests/test_dereference.py

@@ -1171,6 +1171,30 @@ class FieldTest(unittest.TestCase):
 
         self.assertEqual(2, len([brand for bg in brand_groups for brand in bg.brands]))
 
+    def test_dereferencing_embedded_listfield_referencefield(self):
+        class Tag(Document):
+            meta = {'collection': 'tags'}
+            name = StringField()
+
+        class Post(EmbeddedDocument):
+            body = StringField()
+            tags = ListField(ReferenceField("Tag", dbref=True))
+
+        class Page(Document):
+            meta = {'collection': 'pages'}
+            tags = ListField(ReferenceField("Tag", dbref=True))
+            posts = ListField(EmbeddedDocumentField(Post))
+
+        Tag.drop_collection()
+        Page.drop_collection()
+
+        tag = Tag(name='test').save()
+        post = Post(body='test body', tags=[tag])
+        Page(tags=[tag], posts=[post]).save()
+
+        page = Page.objects.first()
+        self.assertEqual(page.tags[0], page.posts[0].tags[0])
+
 if __name__ == '__main__':
     unittest.main()