Question

所以我的问题很简单，我有2个列表框和一个按钮。当在listbox2中选择一个项目并单击该按钮时，我想将所选项目添加到listbox1。

在我添加第二项之前，所有接缝都能正常工作。然后listbox1不会刷新它的项目......

<body>
<form id="form1" runat="server">
    <asp:ScriptManager runat="server"></asp:ScriptManager>
    <div>
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
                <asp:ListBox ID="ListBox1" runat="server"></asp:ListBox>
            <asp:ListBox ID="ListBox2" runat="server"></asp:ListBox>
                <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />
            </ContentTemplate>
        </asp:UpdatePanel>
    </div>
    </form>
</body>
public partial class Default2 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            ListBox2.Items.Add(new ListItem("1", "1"));
            ListBox2.Items.Add(new ListItem("2", "2"));
            ListBox2.Items.Add(new ListItem("3", "3"));
            ListBox2.Items.Add(new ListItem("4", "4"));
            ListBox2.Items.Add(new ListItem("5", "5"));
        }
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        if (ListBox2.SelectedIndex != -1)
        {
            ListBox1.Items.Add(ListBox2.SelectedItem);
        }
    }
}

Answer 1

您可以将UpdateMode=conditional添加到UpdatePanel

并设置<asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" />

  <asp:ScriptManager runat="server"></asp:ScriptManager>
    <div>
        <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
            <ContentTemplate>
                <asp:ListBox ID="ListBox1" runat="server"></asp:ListBox>
                <asp:ListBox ID="ListBox2" runat="server"></asp:ListBox>
                <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />
            </ContentTemplate>

            <Triggers>
                <asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" />
            </Triggers>

        </asp:UpdatePanel>
    </div>

Answer 2

找到解决方案:) 问题是Listbox1 SelectionMode = Single ...所以当返回结果时错误是在客户端。解决方案是在将项目添加到其他列表之前取消选择该项目。（或使用所选值中的值和文本制作新内容）

 protected void Button1_Click(object sender, EventArgs e)
    {
        if (ListBox2.SelectedIndex != -1)
        {

            ListItem item = ListBox2.SelectedItem;
            item.Selected = false;
            ListBox1.Items.Add(item);

        }
    }

Asp.net updatepanel Listbox没有刷新布局

2 个答案: