asp.net中的列表框没有得到选定的项目

问题描述

我有多个下拉菜单和我网页中的列表框.

I have multiple dropdown & listbox in my webpage.

我正在尝试从 lstCatID 列表框中获取 CategoryID 列表，我可以使用类别名称填充列表框.

I am trying to get a list of CategoryID from a lstCatID listbox i am able to populate the listbox with category name.

如果我在第一次尝试时没记错，我的代码运行良好，之后我做了一些更改，然后它声明总是选择第一个项目 x 时间

If i remember correctly in first attempt my code worked fine, after that i made some change then it stated to always get the first item selected x No. of time

<asp:ListBox ID="lstCatID" runat="server" DataTextField="CategoryName" 
                DataValueField="CategoryID" SelectionMode="Multiple" CssClass="lstListBox">
 </asp:ListBox>



protected void Button1_Click(object sender, EventArgs e)
{
    string CatID = string.Empty;
    foreach (ListItem li in lstCatID.Items)
    {
        if (li.Selected == true)
        {
           // Response.Write();
            CatID += lstCatID.SelectedItem.Value + ",";
        }
    }
    Response.Write(CatID);
}

我不确定出了什么问题，我检查了 MSDN，它显示的方法完全相同.

I am not sure what is going wrong i checkd MSDN it show exactly the same way of doing it.

可能是我做错了什么.

只需使用 Firefox 添加，我就能看到多个选定的值具有选定的属性.

Just to add using firefox i am able to see multiple selected value have selected property.

<option value="3" selected="selected">One</option>
<option value="2">Two</option>
<option value="29" selected="selected">Three</option>
<option value="25" selected="selected">Four</option>
<option value="22" >Five</option>

在这种情况下，我的输出将是 3,3,3

My output in this case will be 3,3,3

我会很感激这方面的帮助

I would appreciate help in this regard

推荐答案

您每次都将其设置为相同的值:

You are setting it to the same value every time:

foreach (ListItem li in lstCatID.Items)
{
    if (li.Selected == true)
    {
       // you are always using lstCatID.SelectedItem.Value.
        CatID += lstCatID.SelectedItem.Value + ",";
    }
}

当你真正想要你的循环中被选中的项目的值时:

When you actually want the value of the item in your loop that is selected:

foreach (ListItem li in lstCatID.Items)
{
    if (li.Selected == true)
    {
        // get the value of the item in your loop
        CatID += li.Value + ",";
    }
}

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