Hi
If we populate the dropdown on client side using web service and jquery, it will give very good performance as compare to server side method.
These are the few steps to do this task
It is very much similar to this post. Here we have to do the few changes in web service
1. Add this namespace in web service
using System.Web.Script.Services;
2. Add this code below the web method
[ScriptMethod(ResponseFormat = ResponseFormat.Json, UseHttpGet = true)]
Complete code is like this
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;
using Test;
using System.Data.SqlClient;
using System.Data;
using System.Web.Script.Services;///
/// Summary description for WebService
///[WebService(Namespace = “http://tempuri.org/”)]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.[System.Web.Script.Services.ScriptService]
public class WebService : System.Web.Services.WebService {[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json, UseHttpGet = true)]
public List FindAllCountries()
{
List locations = new List();
string connectionString =
“Data Source=.;Initial Catalog=Test;Integrated Security=True”;
using (SqlConnection connection = new SqlConnection(connectionString))
{
using (SqlCommand command = new SqlCommand())
{
command.Connection = connection;
command.CommandText = “SelectAllCountries”;
command.CommandType = CommandType.StoredProcedure;
connection.Open();
using (SqlDataReader dataReader = command.ExecuteReader())
{
Location location;
if (dataReader != null)
while (dataReader.Read())
{
location = new Location();
location.CountryID = (int)dataReader[“CountryID”];
location.CountryName = Convert.ToString(dataReader[“CountryName”]);
locations.Add(location);
}
}
}
}
return locations;
}}
In default page we have to call the web service using Jquery like this
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default_Jquery1.aspx.cs" Inherits="WebService_Test_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title></title>
<script type="text/javascript"
src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js"></script><script language="javascript" type="text/javascript">
$(document).ready(function() {
$.ajax({
type: "GET",
url: "../WebService.asmx/FindAllCountries",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function(response) {
var ddl1 = response.d;
for (var i = 0; i < ddl1.length; i++) {
var selectOption = $(document.createElement(‘option’));
$(‘#ddl1’).append(selectOption.val(ddl1[i].CountryID).html(ddl1[i].CountryName)
);
}
},
failure: function(errMsg) {
$(‘#errMessage’).text(errMsg);
}
});
});
</script></head>
<body>
<form id="form1" runat="server">
<div><select id="ddl1">
<option>Select</option>
</select>
<div id="errMessage"></div></div>
</form>
</body>
</html>
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