update

app/service/forumThreadService.js

@@ -1008,7 +1008,7 @@ function getMobileSubThreads(doc, sort, callback) {
                 });
                 var obj = {};
                 obj.items = list;
-                var newDoc = {};
+                var newDoc = doc.toObject();
                 newDoc.subThreads = obj;
                 cb(null, newDoc);
             }