我设计了以下代码，将 DropDownList 嵌套在 DataList 中，其中包含一些值问题。现在如何获取选定的值。
我想用 DropDownList 的选定值更新 DataList 中的 Label。每次用户更改 DropDownList 所选值时都应该发生
我想要这样的东西:
protected void DDList_SelectedIndexChanged(object sender, EventArgs e)
{
selectedData.Text = myDropDownList.SelectedValue;
}
经过大量阅读，我发现了这个
(e.Item.FindControl("DDList") as DropDownList).SelectedValue = DataBinder.Eval(e.Item, "Value").ToString();
但是每次更改所选项目时如何将此值分配给标签？
到目前为止我写的代码是
ASPX代码:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:DataList runat="server" ID="DataList1" OnItemDataBound="DataList1_ItemDataBound" DataKeyField="Class">
<ItemTemplate>
<table>
<tr>
<td>
<label>
<%#Eval("ID")%>:
</label>
</td>
<td>
<label>
<%#Eval("Name")%>
</label>
</td>
<td>
<label>
<%#Eval("Class")%>
</label>
</td>
<td>
<asp:DropDownList runat="server" ID="DDList" OnSelectedIndexChanged="DDList_SelectedIndexChanged"></asp:DropDownList>
</td>
<td>
<asp:Label runat="server" ID="selectedData" ForeColor="Red"></asp:Label>
</td>
</tr>
</table>
<br />
</ItemTemplate>
</asp:DataList>
</div>
</form>
C#代码:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
PopulateData();
}
}
private void PopulateData()
{
DataTable dt = new DataTable();
dt.Columns.Add(new DataColumn("ID", typeof(int)));
dt.Columns.Add(new DataColumn("Name", typeof(string)));
dt.Columns.Add(new DataColumn("Class", typeof(int)));
DataRow dr1 = dt.NewRow();
dr1["ID"] = 1;
dr1["Name"] = "Ishan";
dr1["Class"] = 3;
dt.Rows.Add(dr1);
DataRow dr2 = dt.NewRow();
dr2["ID"] = 2;
dr2["Name"] = "Sumit";
dr2["Class"] = 5;
dt.Rows.Add(dr2);
DataRow dr3 = dt.NewRow();
dr3["ID"] = 3;
dr3["Name"] = "Manish";
dr3["Class"] = 4;
dt.Rows.Add(dr3);
DataList1.DataSource = dt;
DataList1.DataBind();
}
protected void DataList1_ItemDataBound(object sender, DataListItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
{
var myDropDownList = e.Item.FindControl("DDList") as DropDownList;
int currentItemID = int.Parse(this.DataList1.DataKeys[e.Item.ItemIndex].ToString());
myDropDownList.DataSource = PopulateDDList(currentItemID);
myDropDownList.DataValueField = "ID";
myDropDownList.DataTextField = "Value";
myDropDownList.DataBind();
(e.Item.FindControl("DDList") as DropDownList).SelectedValue = DataBinder.Eval(e.Item, "Value").ToString();
}
}
private DataTable PopulateDDList(int count)
{
DataTable dt = new DataTable();
dt.Columns.Add(new DataColumn("ID", typeof(int)));
dt.Columns.Add(new DataColumn("Value", typeof(string)));
for(int i = 0; i < count; i++)
{
DataRow dr = dt.NewRow();
dr["ID"] = i;
dr["Value"] = Convert.ToString(i+1);
dt.Rows.Add(dr);
}
return dt;
}
}
最佳答案
您可以使用sender 的NamingContainer 来查找Label。
protected void DDList_SelectedIndexChanged(object sender, EventArgs e)
{
//cast the sender back to a dropdownlist
DropDownList ddl = sender as DropDownList;
//get the namingcontainer from the dropdownlist and cast it as a datalistitem
DataListItem item = ddl.NamingContainer as DataListItem;
//now use findcontrol to find the label in the datalistitem
Label lbl = item.FindControl("selectedData") as Label;
lbl.Text = ddl.SelectedValue;
}
关于c# - 从 DataList 中的 DropDownList 获取选定值，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42794524/