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Home - Tutorials - AJAX - Creating & Changing Dynamic Controls using AJAX & VB |
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This tutorial shows how we can use AJAX to dynamically interact with controls, without using postback or refreshing the page. VB version.
This tutorial will demonstrate how we can dynamically create and alter controls using AJAX. This tutorial is very simple, but the principle can be applied to any control, giving you powerful results.
In the tutorial, we will simply create 3 custom controls and use a dropdown list to change these controls.
We create three WebControls: BlueControl.ascx, GreenControl.ascx and RedControl.ascx all with similar code as below:
<%@ Control Language="VB" AutoEventWireup="true" CodeFile="BlueControl.ascx.vb" Inherits="BlueControl" %>
<div style="background-color: Blue; width: 200px; height: 200px">
</div> |
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On Default.aspx, we add a ScriptManager, UpdatePanel, DropDownList and a PlaceHolder:
<form id="frmMain" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server" /> <h2>Using AJAX to Dynamically Create Controls</h2> <div>
<table width="500">
<tr valign="top">
<td style="width: 150px">
<span style="font-size: 10pt">Choose Color:<br /> </span> <asp:DropDownList ID="ddColor" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddColor_SelectedIndexChanged" Width="100px">
<asp:ListItem Selected="True">Red</asp:ListItem> <asp:ListItem>Blue</asp:ListItem> <asp:ListItem>Green</asp:ListItem> </asp:DropDownList></td> <td>
<asp:UpdatePanel ID="updatePanel" runat="server">
<ContentTemplate>
<asp:PlaceHolder ID="placeHolder" runat="server"></asp:PlaceHolder> </ContentTemplate> <Triggers>
<asp:AsyncPostBackTrigger ControlID="ddColor" /> </Triggers> </asp:UpdatePanel> </td> </tr> </table> </div> |
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The code-behind will look something like this:
Imports System
Imports System.Data
Imports System.Configuration
Imports System.Web
Imports System.Web.Security
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports System.Web.UI.HtmlControls
Partial Class _Default
Inherits System.Web.UI.Page Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
SetColor() End Sub Private Sub SetColor()
Dim c As Control = Page.LoadControl(ddColor.SelectedValue & "Control.ascx")
placeHolder.Controls.Clear()
placeHolder.Controls.Add(c) End Sub Protected Sub ddColor_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddColor.SelectedIndexChanged
SetColor() End Sub |
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Web.config will look something like this:
<?xml version="1.0"?>
<configuration>
<configSections>
<sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
<sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
<section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="MachineToApplication"/> <sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
<section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="Everywhere"/>
<section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="MachineToApplication"/>
<section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="MachineToApplication"/> </sectionGroup> </sectionGroup> </sectionGroup> </configSections> <system.web>
<pages>
<controls>
<add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> </controls> </pages> <!--
Set compilation debug="true" to insert debugging
symbols into the compiled page. Because this
affects performance, set this value to true only
during development. --> <compilation debug="true">
<assemblies>
<add assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> </assemblies> </compilation> <httpHandlers>
<remove verb="*" path="*.asmx"/> <add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> <add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> <add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" validate="false"/> </httpHandlers> <httpModules>
<add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> </httpModules> </system.web> <system.web.extensions>
<scripting>
<webServices>
<!-- Uncomment this line to customize maxJsonLength and add a custom converter -->
<!-- <jsonSerialization maxJsonLength="500">
<converters>
<add name="ConvertMe" type="Acme.SubAcme.ConvertMeTypeConverter"/> </converters> </jsonSerialization> -->
<!-- Uncomment this line to enable the authentication service. Include requireSSL="true" if appropriate. -->
<!-- <authenticationService enabled="true" requireSSL = "true|false"/> -->
<!-- Uncomment these lines to enable the profile service. To allow profile properties to be retrieved
and modified in ASP.NET AJAX applications, you need to add each property name to the readAccessProperties and
writeAccessProperties attributes. -->
<!-- <profileService enabled="true"
readAccessProperties="propertyname1,propertyname2"
writeAccessProperties="propertyname1,propertyname2" /> -->
</webServices>
<!-- <scriptResourceHandler enableCompression="true" enableCaching="true" /> --> </scripting> </system.web.extensions> <system.webServer>
<validation validateIntegratedModeConfiguration="false"/> <modules>
<add name="ScriptModule" preCondition="integratedMode" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> </modules> <handlers>
<remove name="WebServiceHandlerFactory-Integrated"/> <add name="ScriptHandlerFactory" verb="*" path="*.asmx" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> <add name="ScriptHandlerFactoryAppServices" verb="*" path="*_AppService.axd" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> <add name="ScriptResource" preCondition="integratedMode" verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> </handlers> </system.webServer> |
Download the Full Working Version of this Project written with Visual Studio.NET VB 2005 Here!
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