如何在asp中获取列表框中的选定项?

时间:2015-02-24 10:10:35

标签: c# asp.net listbox

我使用列表框以字符串形式查看数据库的某些记录。但现在有两个不同的问题: 1.选择更改不会通过双击或单击调用,只会在您选择项目并按返回时调用。 2.即使选择更改调用,selectedIndex返回-1,选中的值为null。 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>

我在VS2013中通过观察窗检查的Cs代码并没有什么特别之处:

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:

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]);
}

当我按下删除按钮时,我甚至尝试获取所选索引,但结果是相同的。

1 个答案:

答案 0 :(得分:0)

将您的代码绑定在!Page.IsPostBack块中。确保代码不会在回发时执行。如果你在PostBack上绑定ListView,你将失去GridView的所有状态,包括被触发的事件,SelectedIndex等。

Page.IsPostBack Property

  

获取一个值,该值指示是否为该页面呈现页面   第一次或正在加载以响应回发。

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

通常控件是在Page_Load方法中绑定的,你可能需要在那里检查Page.IsPostBack。