ขอแนวทาง กดที่Products.แล้วให้เก็บให้แสดงรายชื่อสินค้าแล้วเก็บค่าไว้ และสามารถสั่งซื้อสินค้าได้!

[Serializable]
public class ProductItem
{
    private string _ID = string.Empty;
    private string _Label = string.Empty;
    private double _Price = 0;
    private double _Quantity = 0;
    private int _Flag = 0;

    public string ID { get { return _ID; } set { _ID = value; } }
    public string Label { get { return _Label; } set { _Label = value; } }
    public double Price { get { return _Price; } set { _Price = value; } }
    public double Quantity { get { return _Quantity; } set { _Quantity = value; } }
    public int Flag { get { return _Flag; } set { _Flag = value; } }

    public ProductItem() { }
    public ProductItem(string varID, string varLabel, double varPrice, double varQuantity, int varFlag)
    {
        this.ID = varID;
        this.Label = varLabel;
        this.Price = varPrice;
        this.Quantity = varQuantity;
        this.Flag = varFlag;
    }

    public override string ToString()
    {
        return this.ID + "|" + this.Label + "|" + this.Price.ToString("#,##0.00")
            + "|" + this.Quantity.ToString("#,##0.00") + "|" + this.Flag.ToString();
    }
}

[Serializable]
public class ProductBasket : List<ProductItem>
{
    public ProductBasket() : base() { }

    public void AddItemToBasket(ProductItem varItem)
    {
        /*
        //Linq pattern if u like it
        ProductItem oldItem = (from e in this.ToArray()
                               where e.ID== varItem.ID
                               select e).First();
        */
        //convention style
        ProductItem oldItem = null;
        foreach (ProductItem sItem in this.GetEnumerator())
        {
            if (sItem.ID == varItem.ID)
            {
                oldItem = sItem;
                break;
            }
        }

        ProductItem newItem = varItem ;
        if (oldItem != null) // founded item           
        {
            //add quantity
            newItem.Quantity += oldItem.Quantity;
            this.Remove(oldItem);
        }

        this.Add(newItem);
    }
}

ProductBasket myBasket = new ProductBasket ();
Session["basket"] = myBasket ;