public ActionResult Index()
        {
            List <TreeViewNode> nodes = new List <TreeViewNode>();

            var dao      = new UserGroupDao();
            var entities = dao.GetUserGroups();


            //Loop and add the Parent Nodes.
            foreach (UserGroup type in entities)
            {
                nodes.Add(new TreeViewNode {
                    id = type.ID.ToString(), parent = "#", text = type.Name
                });
            }


            var childEntity = dao.GetRoleByGroup();

            // Loop and add the Child Nodes.
            foreach (UserRoleByGroupModel subType in childEntity)
            {
                nodes.Add(new TreeViewNode {
                    id = subType.role.ID.ToString(), parent = subType.userGroup.ID.ToString(), text = subType.role.Name
                });
            }

            //Serialize to JSON string.
            ViewBag.Json = (new JavaScriptSerializer()).Serialize(nodes);

            SetAlert("Load thành công", "success");
            return(View());
        }