动态 DropDownList 索引事件不触发

Question

在 ASP.Net 应用程序中，我有一个用户可以购买商品的页面。为此，他们使用两个 DropDownLists：一个用于查找他们的 itemID，第二个用于选择他们想要购买的物品数量，命名为 Amount 和 PurchasedItemIDs。每件物品都有单独的草药/宝石价格。

我想更改一个名为 TotalPrice 的标签，以便在用户更改所选索引时计算药草和宝石的总价。

我做了一个活动：

protected void Price_Changed_Event(object sender, EventArgs e)
    {
        int HerbPrice = -1;
        int GemPrice = -1;
        int AmountPurchased = int.Parse(Amount.SelectedValue);
        //Code to get the price out of the items. If it's relevant, ask for it.
        foreach (shopItem t in Items)
        {
            if (t.ID == int.Parse(PurchaseItemIDs.SelectedValue))
            {
                HerbPrice = t.herbCost*AmountPurchased;
                GemPrice = t.gemCost * AmountPurchased;
            }
        }
        if (HerbPrice == -1 || GemPrice == -1)
            throw new Exception("ItemID not found.");
        else
            TotalPrice.Text = "Herbs: "+ HerbPrice + ", Gems: " + GemPrice; 
    }

我编辑了下拉列表：

<asp:DropDownList ID="PurchaseItemIDs" runat="server" Width="120px" 
    BackColor="#F6F1DB" ForeColor="#7d6754" Font-Names="Andalus" CssClass="ddl" 
    onselectedindexchanged="Price_Changed_Event" 
    ontextchanged="Price_Changed_Event">
</asp:DropDownList>
<asp:DropDownList ID="Amount" runat="server" Width="120px" BackColor="#F6F1DB" 
    ForeColor="#7d6754" Font-Names="Andalus" CssClass="ddl" 
    onselectedindexchanged="Price_Changed_Event" 
    ontextchanged="Price_Changed_Event">
</asp:DropDownList>

尽管如此，当我更改要购买的商品数量时，标签的文本与默认值相比并没有发生任何变化。我在事件开始时设置了一个断点 - 它没有被触发。

编辑：页面加载内容：

if (!Page.IsPostBack)
            {
                for (int i = 1; i <= 100; i++)
                {
                    ListItem t = new ListItem();
                    t.Value = "" + i;
                    t.Text = "" + i;
                    Amount.Items.Add(t);
                }
                foreach (int id in from item in getItemsForUser(((User)Session["User"]).Username) select item.ID)
                {
                    ListItem itm = new ListItem();
                    itm.Text = "" + id;
                    itm.Value = "" + id;
                    PurchaseItemIDs.Items.Add(itm);
                }
                TotalPrice.Text = "Pick an item and an amount to see the price.";
            }
             //irrelevant stuff.

我做错了什么？

Answer 1

将 AutoPostBack="true" 添加到您的下拉列表控件：

<asp:DropDownList ID="PurchaseItemIDs" AutoPostBack="true"  runat="server" Width="120px" 
BackColor="#F6F1DB" ForeColor="#7d6754" Font-Names="Andalus" CssClass="ddl" 
onselectedindexchanged="Price_Changed_Event" 
ontextchanged="Price_Changed_Event">
</asp:DropDownList>

<asp:DropDownList ID="Amount" AutoPostBack="true" runat="server" Width="120px" BackColor="#F6F1DB" 
ForeColor="#7d6754" Font-Names="Andalus" CssClass="ddl" 
onselectedindexchanged="Price_Changed_Event" 
ontextchanged="Price_Changed_Event">
</asp:DropDownList>

动态 DropDownList 索引事件不触发

Dynamic DropDownList index event does not trigger

c#

asp.net

drop-down-menu