In this article, you will learn how to use the DropDownList's SelectedIndexChanged event
The SelectedIndexChanged event of ASP.Net DropDownList
HTML
<asp:DropDownList ID="ddlCity" runat="server" AutoPostBack = "true" OnSelectedIndexChanged = "OnSelectedIndexChanged">
<asp:ListItem Text="Delhi" Value="1" />
<asp:ListItem Text="Mumbai" Value="2" />
<asp:ListItem Text="Noida" Value="3" />
</asp:DropDownList>C#
protected void OnSelectedIndexChanged(object sender, EventArgs e)
{
string message = ddlCity.SelectedItem.Text + " - " + ddlCity.SelectedItem.Value;
ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('" + message + "');", true);
}How to use the DropDownList's SelectedIndexChanged event
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs"
Inherits="_Default" %>
<!DOCTYPE html>
<html>
<head>
<title>Asp.Net Repeater Control</title>
</head>
<body>
<form id="form1" runat="server">
<div style="font:13px Verdana;width:310px;">
<asp:ScriptManager ID="scriptManager" runat="server" EnablePageMethods="true" />
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<h3>Asp.Net Repeater Control</h3>
<%--THE REPEATER CONTROL.--%>
<asp:Repeater id="rp" runat="server">
<%--HEADER OF THE REPEATER--%>
<HeaderTemplate>
<table border="0" width="200px">
</HeaderTemplate>
<%--SHOWING ITEMS--%>
<ItemTemplate>
<tr>
<td style="padding:2px;
border:solid 1px #CCC;">
<asp:Label Text='<%# Container.DataItem.ToString() %>'
runat="server"></asp:Label>
</td>
</tr>
</ItemTemplate>
<%--ALTERNATE TEMPLATE (SHOWING ITEMS IN DIFFERENT COLOR--%>
<AlternatingItemTemplate>
<tr>
<td style="padding:2px;
border:solid 1px #CCC;
background:#EAF7FB;
width:200px;">
<asp:Label Text='<%# Container.DataItem.ToString() %>'
runat="server"></asp:Label>
</td>
</tr>
</AlternatingItemTemplate>
<%--REPEATER FOOTER--%>
<FooterTemplate>
</table>
<div style="padding:20px 0;">
<asp:Label ID="lblFoot" runat="server"></asp:Label>
</div>
</FooterTemplate>
</asp:Repeater>
<%--BUTTON CONTROL--%>
<asp:Button ID="btVF" Text="View Files" AutoPostBack="true"
OnClick="Show"
Font-Names="sanserif"
Font-Italic="true"
Font-Size="155%"
runat="server" />
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="PostBackTrigger" />
</Triggers>
</asp:UpdatePanel>
</div>
</form>
</body>
</html>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e) {}
protected void Show(object sender, EventArgs e)
{
DirectoryInfo Folder = new DirectoryInfo(Server.MapPath("Files\\"));
FileInfo[] fileList = Folder.GetFiles("*.*");
//BIND THE FILE LIST WITH THE REPEATER CONTROL.
rp.DataSource = fileList;
rp.DataBind();
}
}
Adding the <AlternatingTemplate> below the <ItemTemplate> will show files with a different background color for every alternate row.
<AlternatingItemTemplate>
<div style="padding:3px; border:solid 1px #FFF; background:#black">
<asp:Label Text='<%# Container.DataItem.ToString() %>' runat="server"></asp:Label>
</div>
</AlternatingItemTemplate>
</AlternatingItemTemplate>
<SeparatorTemplate><hr />
</SeparatorTemplate>
Add the <HeaderTemplate> element just above the <ItemTemplate>
<HeaderTemplate>
<div style="padding-bottom:20px"><strong>Files</strong> (Header)</div>
</HeaderTemplate>
Repeater with <FooterTemplate> element
<FooterTemplate>
<div style="padding-top:20px"><asp:Label ID="lblFooter" runat="server"></asp:Label></div>
</FooterTemplate>
Code Behind In C#
Control ft = rp.Controls[rep.Controls.Count - 1].Controls[0];
Label lbl_Footer = ft.FindControl("lblFooter") as Label;
lbl_Footer.Text = "Showing total <b>" + fileList.Length + "</b> files in the Footer.";