【发布时间】：2012-10-20 18:10:24
【问题描述】：
我想弄清楚如何通过网络浏览器更改客户的订单。客户将订购带有产品 ID（键）、产品名称、产品价格和他想要的数量的项目。 我想知道如何通过用不同数量的相同物品替换旧数量的旧物品来更改他的订单所以基本上点击选择物品并放置他希望的 2 个不同数量购买。购物车包含购买的物品，所以我想知道如何从购物车中销毁 OrderItem 然后重新创建它。
当我的代码找到购物车中已经存在的密钥时，需要将其销毁并使用新的 Quantity（来自网络应用程序的文本框）重新创建。
protected void btnOrder_Click(object sender, EventArgs e)
{
//Check for Shoppingcart object
// Create first if not there
if (Session["cart"] == null)
Session["cart"] = new ShoppingCart();
int quantity = 0;
// make sure there is text
if (txtQuantity.Text.Trim().Length != 0)
{
quantity = int.Parse(txtQuantity.Text);
if (((ShoppingCart)Session["cart"]).
keyExists(int.Parse(productID.Text)))
{
//Here I should Destroy the current item that exists and replace with new one
}
else // This is a new item
{
// Make the item
OrderItem item = new OrderItem(
int.Parse(productID.Text), productName.Text,
double.Parse(productPrice.Text),
int.Parse(txtQuantity.Text));
// add to cart
((ShoppingCart)Session["cart"]).addToCart(item);
}
// How does this work? Who is sender?
this.btnReturn_Click(sender, e);
}
else
{
Response.Write("Nothing Ordered<br>You must order some of the product or return to the Catalog");
}
这里是 OrderItem 对象
public class OrderItem
{
private int productID;
private string prodName;
private double unitPrice;
private int quantityOrdered;
private string exceptionStr;
public OrderItem(int id, string name, double price, int quantity)
{
prodName = name;
exceptionStr = "Numeric data must not be negative";
if ( id < 0 || price < 0 || quantity < 0)
{
throw new System.ArgumentException(exceptionStr);
}
else
{
productID = id;
unitPrice = price;
quantityOrdered = quantity;
}
}
#region Public Properties
public int ProductID
{
get
{
return productID;
}
}
public string ProductName
{
get
{
return prodName;
}
}
public double UnitPrice
{
get
{
return unitPrice;
}
}
public int QuantityOrdered
{
get
{
return quantityOrdered;
}
set
{
if( value < 0 )
{
throw new ArgumentException(exceptionStr);
}
else
{
quantityOrdered = value;
}
}
}
#endregion
}
这是供您查看的购物车：
public class ShoppingCart : IEnumerable
{
private SortedList theCart;
public ShoppingCart() {
theCart = new SortedList();
} // end of Constructor
public bool HasItems {
get{
bool hasItems = false;
if( theCart.Count > 0 )
hasItems = true;
return hasItems;
}
set {
// ignore this is read only
}
} // end of HasItems
public void addToCart(OrderItem item) {
theCart.Add(item.ProductID, item);
}// AddToCaArt
/// <summary>
/// deletes item that is passed
/// </summary>
/// <param name="item"></param>
public void deleteFromCart(OrderItem item)
{
theCart.Remove(item.ProductID);
} // end deleteFromCart
/// <summary>
/// deletes the item with this id key
/// </summary>
/// <param name="id"></param>
public void deleteFromCart(int id)
{
theCart.Remove(id);
} // end deleteFromCart
public OrderItem[] getCartContents()
{
// need to create stuff
OrderItem[] stuff = null;
theCart.Values.CopyTo(stuff, 0);
return (stuff);
} // end getCartContents
public bool keyExists(int ID) {
return theCart.ContainsKey(ID);
}// end keyExists
public ICollection Values
{
get
{
return theCart.Values;
}
}
#region IEnumerable Members
public IEnumerator GetEnumerator()
{
return theCart.GetEnumerator();
}
#endregion
}
【问题讨论】：
-
ShoppingCart（addToCart添加的）中存储了哪种类型的集合？ -
你能发布 OrderItem 和 ShoppingCart 类型代码吗？
-
它们是SortedLists，addToCart将productID和客户选择的item添加到SortedList名称theCart中，ShoppingCart和OrderItem的code就起来了。
-
除非您再次销毁并存储，否则您无法更改存储在会话中的对象的变量。
-
此外，当您完成解决方案后，请尝试将您的代码发布到 codereview.stackexchange.com... 在我看来，设计和代码风格需要许多改进。