public ActionResult _ListAppointment(int id_center, string startdate, string enddate)
        {
            int minRow = 0;
            int maxRow = 0;

            int.TryParse(HttpContext.Request["start"], out minRow);
            int length = 10;

            int.TryParse(HttpContext.Request["length"], out length);
            maxRow = length;
            int draw = 0;

            int.TryParse(HttpContext.Request["draw"], out draw);
            string search      = HttpContext.Request["search[value]"].Trim();
            int    currentPage = (minRow / 10) + 1;
            int    total;
            var    result = rp.GetListAppointmetByOffset(id_center, startdate, enddate, search, currentPage, maxRow, out total);

            return(Content(JsonConvert.SerializeObject(new
            {
                data = result,
                draw = draw,
                recordsFiltered = total,
                recordsTotal = total
            })));
        }