public JsonResult GroupDropList(string filterExpression) { GroupRepository rep = new GroupRepository(); if (HttpContext.Cache["GroupDropList"] == null) { DataTable list = rep.GetDropListSource(); HttpContext.Cache.Add("GroupDropList", list, null, DateTime.Now.AddMinutes(5), TimeSpan.Zero, CacheItemPriority.High, null); } DataTable source = (DataTable)HttpContext.Cache["GroupDropList"]; filterExpression = DFT.HandleExpress(filterExpression); List <DropListSource> dropList = rep.DropList(source, filterExpression); return(DropListJson(dropList)); }