Callback Panel

• Oct 29, 2020
• 2 minutes to read

The BootstrapCallbackPanel control represents a container area whose content can be updated using an AJAX-based callback technology. The collection of the Callback Panel’s child controls can be accessed via the ASPxPanelContainerBase.Controls property.

The Callback Panel control implements a comprehensive client-side, and server-side functionality that enables updating its content on demand via callbacks. The client-side object model contains the client object for the Callback Panel control (BootstrapClientCallbackPanel), its method required to send a callback to the server (BootstrapClientCallbackPanel.PerformCallback), and methods allowing specific client operations to be performed when a callback sends to and comes from the server side (BootstrapClientCallbackPanel.BeginCallback and BootstrapClientCallbackPanel.EndCallback). Use the control’s BootstrapCallbackPanel.ClientSideEvents property to assign a handler for the available client-side events. An instance of the BootstrapClientCallbackPanel object can be easily identified on the client by using the client programmatic identifier set via the ASPxPanelBase.ClientInstanceName property.

The required server-side processing of a callback sent from the client side by using the BootstrapClientCallbackPanel.PerformCallback method can be performed in a handler of the control’s server-side BootstrapCallbackPanel.Callback event.

The code sample below demonstrates the use of the Bootstrap Callback Panel.

ASPX

<dx:BootstrapButton runat="server" Text="LoadData" AutoPostBack="false">
    <ClientSideEvents Click="function() { CallbackPanel.PerformCallback('Update') }" />
</dx:BootstrapButton>

<dx:BootstrapCallbackPanel runat="server" OnCallback="callbackPanel_Callback" ClientInstanceName="CallbackPanel">
    <ContentCollection>
        <dx:ContentControl>
            <div id="container" runat="server"></div>
        </dx:ContentControl>
    </ContentCollection>
</dx:BootstrapCallbackPanel>

C#

protected void callbackPanel_Callback(object sender, DevExpress.Web.CallbackEventArgsBase e) {
    container.InnerText = e.Parameter;
}

VB.NET

Protected Sub callbackPanel_Callback(ByVal sender As Object, ByVal e As DevExpress.Web.CallbackEventArgsBase)
    container.InnerText = e.Parameter
End Sub