如何获取ASP.NET中列表框的选中项？

Question

我使用列表框以字符串的形式查看数据库中的某些记录，但我遇到了两个问题：

select离子更改不会通过双击或单击调用，它仅在您 select 一个项目并按 return 时调用。
即使调用 selection changed，selectedIndex returns -1 和 selected 值为空。

ASP代码：

<form runat="server">
    <div class="clearfix">
        <asp:ListBox runat="server" ID="g1SeasonsListView" CssClass="adminSeasonsListView"  OnSelectedIndexChanged="g1SeasonsListView_SelectedIndexChanged" />
        <asp:ListBox runat="server" ID="g2SeasonsListView" CssClass="adminSeasonsListView" />
        <asp:ListBox runat="server" ID="g3SeasonsListView" CssClass="adminSeasonsListView" />
    </div>
    <div class="clearfix">
        <asp:Button ID="g1DeleteBtn" Text="Delete" runat="server" OnClick="g1DeleteBtn_Click" CssClass="adminDeleteBtn" />
        <asp:Button ID="g2DeleteBtn" Text="Delete" runat="server" OnClick="g2DeleteBtn_Click" CssClass="adminDeleteBtn" />
        <asp:Button ID="g3DeleteBtn" Text="Delete" runat="server" OnClick="g3DeleteBtn_Click" CssClass="adminDeleteBtn" />
    </div>
</form>

CS代码，我在VS2013中通过watchwindow检查过；没什么特别的:

protected void g1DeleteBtn_Click(object sender, EventArgs e)
{    
}
protected void g2DeleteBtn_Click(object sender, EventArgs e)
{
}
protected void g3DeleteBtn_Click(object sender, EventArgs e)
{    
}
protected void g1SeasonsListView_SelectedIndexChanged(object sender, EventArgs e)
{    
}

当我想更新列表框时，我使用此代码：

private void UpdateListeView()
{
    List<string> seasonsListTemp = null;

    g1SeasonsListView.Items.Clear();
    seasonsListTemp = (from s in database.Gs where s.grade == 1 select s.season).ToList();
    for (int i = 0; i < seasonsListTemp.Count; i++)
        g1SeasonsListView.Items.Add(seasonsListTemp[i]);

    g2SeasonsListView.Items.Clear();
    seasonsListTemp = (from s in database.Gs where s.grade == 2 select s.season).ToList();
    for (int i = 0; i < seasonsListTemp.Count; i++)
        g2SeasonsListView.Items.Add(seasonsListTemp[i]);

    g3SeasonsListView.Items.Clear();
    seasonsListTemp = (from s in database.Gs where s.grade == 3 select s.season).ToList();
    for (int i = 0; i < seasonsListTemp.Count; i++)
        g3SeasonsListView.Items.Add(seasonsListTemp[i]);
}

我什至试图在按下删除按钮时获取 selected 索引，但结果是一样的。

Answer 1

在 !Page.IsPostBack 块中绑定您的代码。这将确保代码不会在回发时执行。如果您在 PostBack 上绑定 ListView，您将失去 GridView 的状态，包括被触发的事件、SelectedIndex 等。

Page.IsPostBack Property

Gets a value that indicates whether the page is being rendered for the first time or is being loaded in response to a postback.

if(!Page.IsPostBack)
{
     UpdateListeView();
}

通常控件绑定在 Page_Load 方法中，您可能需要在那里检查 Page.IsPostBack。

如何获取ASP.NET中列表框的选中项？

How to get the selected item of a listbox in ASP.NET?

c#

asp.net

listbox