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This tutorial will show how we can use AJAX to dynamically generate a list of random names without calling postback. C# version.
This tutorial was created with Microsoft's ASP.NET AJAX Extensions, which can be downloaded at this link
This tutorial makes use of the UpdatePanel control in Visual Studio's AJAX toolbox. It will show you how we can generate random names from a string array at the click of a button, without postback.
The first thing we need to do is start an ASP.NET AJAX-Enabled Web Site within Visual Studio .NET
Then we can add our UpdatePanel, button and label to the ASPX page:
<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server" /> <div>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate><fieldset><legend>Panel with Random Names</legend><br />
<asp:Button ID="Button1" runat="server" Text="Generate Random Names" OnClick="Button1_Click" /> <br /> <asp:UpdateProgress ID="UpdateProgress1" runat="server" DisplayAfter="100" DynamicLayout="true">
<ProgressTemplate><img border="0" src="media/loading.gif" /></ProgressTemplate> </asp:UpdateProgress> <asp:Label ID="lblNames" runat="server"></asp:Label> </fieldset></ContentTemplate> </asp:UpdatePanel> </div> |
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We add the following assembly reference, because we are goingto use a string array to store names:
| using System.Collections.Generic; |
Then we create the string array:
private readonly string[] NAMES = new string[]
{
"Mark", "Tom", "Harry", "Sally", "Sandra", "Paul", "Anastasia", "David", "Alex", "Michael", "Tina", "Zachary", "Bob", "Elise" }; |
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Then we create the method that will choose a list of names at random:
private void FillListBoxRandom()
{
lblNames.Text = ""; List<String> names = new List<string>(); int count = NAMES.Length; for (int i = 1; i < 4; i++) {
System.Threading.Thread.Sleep(100); Random rnd = new Random(); int number = rnd.Next(count); string selName = NAMES[number]; if (!names.Contains(selName)) {
names.Add(selName); } } foreach (string name in names)
lblNames.Text += name + "<BR />"; |
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The code-behind will look something like this:
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Web.UI.MobileControls;
using System.Collections.Generic;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e) { } protected void Button1_Click(object sender, EventArgs e) {
FillListBoxRandom(); } private readonly string[] NAMES = new string[] {
"Mark", "Tom", "Harry", "Sally", "Sandra", "Paul", "Anastasia", "David", "Alex", "Michael", "Tina", "Zachary", "Bob", "Elise" }; private void FillListBoxRandom() {
lblNames.Text = ""; List<String> names = new List<string>(); int count = NAMES.Length; for (int i = 1; i < 4; i++) {
System.Threading.Thread.Sleep(100); Random rnd = new Random(); int number = rnd.Next(count); string selName = NAMES[number]; if (!names.Contains(selName)) {
names.Add(selName); } } foreach (string name in names)
lblNames.Text += name + "<BR />"; } |
Looking for the VB.NET 2005 Version? Click Here! Looking for more ASP.NET Tutorials? Click Here!
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