public ActionResult Add(int id , CartItem ci)
        {

            List<CartItem> cartList = new List<CartItem>();
            if (Session["Index"] == null)
            {
                cartList.Add(new CartItem { id = cartList.Count + 1,items=findItem(id),quantity=ci.quantity });
                //cartList.Add(
                //    new CartItem { id = cartList.Count + 1, items = findItem(id), quantity = 1 });
                //ticket.orderItems = cartList;
                //for (int i =0; i<cartList.Count;i++)
                //{
                //    ticket.subTotal += (double)cartList[i].quantity * cartList[i].items.productPrice;
                //}
                //Session["Index"] = ticket;
            }
            else
            {
                cartList = (List<CartItem>)(((Invoice)Session["Index"]).orderItems);
                if (isExisted(id) == -1)
                {
                    cartList.Add(new CartItem { id = cartList.Count + 1, items = findItem(id), quantity = ci.quantity });
                }
                else
                {
                    cartList[isExisted(id)].quantity +=ci.quantity;
                }
            }
            ticket.orderItems = cartList;
            Session["Add"] = findItem(id);
            Session["Index"] = ticket;
            Session["Cart"] = ((Invoice)Session["Index"]).totalQuantity;
            return RedirectToAction("Index");
        }
 // GET: Cart/Add/id
 public ActionResult Add(int id)
 {
     CartItem ci = new CartItem();
     ci.items = findItem(id);
     ci.quantity = 1;
     return PartialView(ci);
 }