public void AddLunchbox(lunchbox l)
 {
     try
     {
         db.Lunchboxes.Add(l);
         db.SaveChanges();
     }
     catch (Exception ex)
     {
         throw ex;
     }
 }
 public void DeleteLunchbox(long lunchBoxId)
 {
     try
     {
         lunchbox l = FindLunchbox(lunchBoxId);
         db.Lunchboxes.Remove(l);
         db.SaveChanges();
     }
     catch (Exception ex)
     {
         throw ex;
     }
 }
 public void UpdateLunchbox(long lunchBoxId, int quantity)
 {
     try
     {
         lunchbox l = db.Lunchboxes.Find(lunchBoxId);
         l.quantity        = quantity;
         db.Entry(l).State = System.Data.Entity.EntityState.Modified;
         db.SaveChanges();
     }
     catch (Exception ex)
     {
         throw ex;
     }
 }