Telerik is a leading vendor of ASP.NET AJAX, ASP.NET MVC, Silverlight, WinForms and WPF controls and components, as well as .NET Reporting, .NET ORM , .NET CMS, Code Analysis, Mocking, Team Productivity and Automated Testing Tools. Building on its expertise in interface development and Microsoft technologies, Telerik helps customers build applications with unparalleled richness, responsiveness and interactivity. Telerik products help thousands of companies to be more productive and deliver reliable applications under budget and on time.
Version Q2 2011 released 07/12/2011
select

ComboBox / Automatic Load On Demand

Configuration
Filter:
EntityDataSource:

LinqDataSource:

  • RadComboBox supports codeless or Automatic Load On Demand with all kinds of data sources including .NET 3.5's Linq and EntityDataSource.

    Setting up the automatic Load On Demand is straightforward:

    • Set the DataSourceID property to the ID of the data source and the DataTextField and DataValueField properties to the respective fields in the data items returned by it.
    • Set EnableAutomaticLoadOnDemand to true.
    • (Optional) Set ShowMoreResultsBox/EnableVirtualScrolling to true to enable the respective features.
    • (Optional) Set ItemsPerRequest to the number of Items you would like to load per request. The default (-1) loads all Items at once.

    Note: When you use the DataSourceID or DataSource properties to bind RadComboBox during automatic Load On Demand the ItemDataBound event fires normally, which means that you can use it to change the Item's Text and Value properties as well as modify its Attributes collection based on the DataItem, etc.

Source Code

C# VB.NET
Show code in new window Demo isolation steps
  • <%@ Page Language="VB" AutoEventWireup="true" CodeFile="DefaultVB.aspx.vb" Inherits="DefaultVB" %>

    <%@ Register Assembly="System.Web.Entity, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
        Namespace="System.Web.UI.WebControls" TagPrefix="asp" %>
    <%@ Register TagPrefix="qsf" Namespace="Telerik.QuickStart" %>
    <%@ Register TagPrefix="qsf" TagName="Header" Src="~/Common/Header.ascx" %>
    <%@ Register TagPrefix="qsf" TagName="HeadTag" Src="~/Common/HeadTag.ascx" %>
    <%@ Register TagPrefix="qsf" TagName="Footer" Src="~/Common/Footer.ascx" %>
    <%@ Register TagPrefix="telerik" Namespace="Telerik.Web.UI" Assembly="Telerik.Web.UI" %>
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml">
    <head runat="server">
        <title>Untitled Page</title>
        <qsf:HeadTag runat="server" ID="Headtag1"></qsf:HeadTag>
        <!-- custom head section -->
        <style type="text/css">
            span.text
            {
                float: left;
                font: 13px 'Segoe UI' , Arial, sans-serif;
                color: #4888a2;
                display: block;
                width: 150px;
                padding: 2px 20px 0 0;
            }
            
            .qsfConfig input
            {
                margin-left: 50px;
                position: relative;
                top: 1px;
            }
        </style>
        <!-- end of custom head section -->
    </head>
    <body class="BODY">
        <form id="mainForm" method="post" runat="server">
        <telerik:RadScriptManager ID="RadScriptManager1" runat="server" />
        <qsf:Header ID="Header1" runat="server" NavigationLanguage="VB"></qsf:Header>
        <telerik:RadAjaxPanel ID="RadAjaxPanel1" runat="server">
        <qsf:ConfiguratorPanel runat="server" ID="ConfigurationPanel1" Title="Configuration" Expanded="true">
            <span class="title">Filter:</span>
            <asp:RadioButton ID="FilterStartsWith" runat="server" AutoPostBack="true" Text="StartsWith" Checked="true" GroupName="Filter" />
            <asp:RadioButton ID="FilterContains" runat="server" AutoPostBack="true" Text="Contains" GroupName="Filter" />
        </qsf:ConfiguratorPanel>
        <!-- content start -->
        <span class="text">EntityDataSource: </span>
        <telerik:RadComboBox ID="RadComboBox1" runat="server" Height="180px" Width="220px"
            DataSourceID="EntityDataSource1" DataTextField="ContactName" DataValueField="ContactName"
            EnableAutomaticLoadOnDemand="true" ShowMoreResultsBox="true" EnableVirtualScrolling="true"
            ItemsPerRequest="10">
        </telerik:RadComboBox>
    <asp:EntityDataSource ID="EntityDataSource1" runat="server" ConnectionString="name=NorthwindEntities"
    DefaultContainerName="NorthwindEntities" EntitySetName="Customers" Select="it.[ContactName]"
    AutoPage="true" OrderBy="it.[ContactName]">
        </asp:EntityDataSource>
        <br />
        <br />
        <span class="text">LinqDataSource: </span>
        <telerik:RadComboBox ID="RadComboBox2" runat="server" Height="180px" Width="220px"
            DataSourceID="LinqDataSource1" DataTextField="ContactName" DataValueField="ContactName"
            EnableAutomaticLoadOnDemand="true" ItemsPerRequest="10" ShowMoreResultsBox="true"
            EnableVirtualScrolling="true">
        </telerik:RadComboBox>
    <asp:LinqDataSource runat="server" ID="LinqDataSource1" ContextTypeName="LinqToSql.NorthwindDataContext"
    OrderBy="ContactName" Select="new (ContactName)" TableName="Customers">
        </asp:LinqDataSource>
        <!-- content end -->
        </telerik:RadAjaxPanel>
        <qsf:Footer runat="server" ID="Footer1"></qsf:Footer>
        </form>
    </body>
    </html>

Get more than expected!

 
 

Take your time to truly experience the power of RadControls for ASP.NET AJAX with a free 60-day trial backed up by Telerik’s unlimited dedicated support.

Download your RadControls for ASP.NET AJAX trial and jumpstart your development with the available Getting Started resources.

If you have any questions, do not hesitate to contact us at sales@telerik.com.

Copyright 2002-2024 © Telerik. All right reserved
Telerik Inc, 201 Jones Rd, Waltham, MA 02451