How to load holidays from database into Gantt

using Syncfusion.JavaScript.Models;
 
public ActionResult Index()
{
   ViewBag.holidays = GetHolidayData();
   //…
   return View();
}
public List<Holiday> GetHolidayData()
{
    List<Holiday> list = new List<Holiday>();
    SqlConnection con = new SqlConnection(WebConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString);//connectionString
    con.Open();
    using (con)
    {
       using (var command = con.CreateCommand())
       {
          command.CommandText = "SELECT * FROM holidayData";
          using (var reader = command.ExecuteReader())
          {
             var indexOfCol1 = reader.GetOrdinal("Day");
             var indexOfCol2 = reader.GetOrdinal("Background");
             var indexOfCol3 = reader.GetOrdinal("Label");                       
             while (reader.Read())
             {
                Holiday obj = new Holiday();
                obj.Day = reader.GetValue(indexOfCol1).ToString();
                obj.Background= reader.GetValue(indexOfCol2).ToString();
                obj.Label = reader.GetValue(indexOfCol3).ToString();                          
                list.Add(obj);
             }
             reader.Close();
          }
       }
       con.Close();
    }
    return list;
}

@(Html.EJ().Gantt("Gantt")
     //..
     .Holidays(ViewBag.holidays)
)
 
@(Html.EJ().ScriptManager())