public ActionResult Index()
 {
     HomeModel model = new HomeModel();
     if (SessionManagement.model != null)
     {
         model = SessionManagement.model;
     }
     return View(model);
 }
        public ActionResult Index(HomeModel model)
        {
            if (!string.IsNullOrEmpty(model.MeetupGroupUrl))
            {
                if (SessionManagement.model == null || SessionManagement.model.MeetupGroupUrl != model.MeetupGroupUrl)
                {
                    string url = getJsonUrl(model.MeetupGroupUrl);
                    MeetupData data = readJson(url);
                    Workbook excel = getExcel(data);
                    model.excel = excel;
                    SessionManagement.model = model;
                }
                else
                {
                    model = SessionManagement.model;
                }
            }

            return View(model);
        }