Merge pull request #583 from Gerrrr/distinct_bug

Fixed bug in distinct method

mongoengine/queryset/base.py

@@ -717,7 +717,10 @@ class BaseQuerySet(object):
             # We may need to cast to the correct type eg. ListField(EmbeddedDocumentField)
             doc_field = getattr(self._document._fields.get(field), "field", None)
             instance = getattr(doc_field, "document_type", False)
-            if instance:
+            EmbeddedDocumentField = _import_class('EmbeddedDocumentField')
+            GenericEmbeddedDocumentField = _import_class('GenericEmbeddedDocumentField')
+            if instance and isinstance(doc_field, (EmbeddedDocumentField,
+                                                   GenericEmbeddedDocumentField)):
                 distinct = [instance(**doc) for doc in distinct]
             return distinct