ASPxCallback Class

A callback control.

Assembly: DevExpress.Web.v19.1.dll

Declaration

C#
VB.NET

public class ASPxCallback :
    ASPxWebComponent

Public Class ASPxCallback
    Inherits ASPxWebComponent

Remarks

The ASPxCallback control allows you to send callbacks from the client side and then process them both on the server and client sides.

Note

The ASPxCallback control cannot update any visual control on a web page. For this purpose, use the ASPxCallbackPanel control that serves as a container. Use the callback panel to send a callback to the server and update any control within the panel.

Create a Callback Control

Design Time

The ASPxCallback control is available on the DX.19.1: Components toolbox tab in the Microsoft Visual Studio IDE.

Drag the control onto a form and customize control settings, or paste the control markup in the page’s source code.

ASPX

<dx:ASPxCallback ID="ASPxCallback1" runat="server">
</dx:ASPxCallback>

using DevExpress.Web;
...
protected void Page_Load(object sender, EventArgs e)
{
    ASPxCallback callback = new ASPxCallback();
    callback.ID = "ASPxCallback2";
    Page.Form.Controls.Add(callback);

    callback.ClientInstanceName = "cb";
    callback.Callback += new CallbackEventHandler(ASPxCallback_Callback);
}
protected void ASPxCallback_Callback(object source, CallbackEventArgs e)
{
    // your code
}

Imports DevExpress.Web
...
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
    Dim callback As ASPxCallback = New ASPxCallback()
    callback.ID = "ASPxCallback2"
    Page.Form.Controls.Add(callback)
    callback.ClientInstanceName = "cb"
    callback.Callback += New CallbackEventHandler(AddressOf ASPxCallback_Callback)
End Sub

Protected Sub ASPxCallback_Callback(ByVal source As Object, ByVal e As CallbackEventArgs)
End Sub

Client-Side API

Availability	Available by default.
Class name	ASPxClientCallback
Access name	ClientInstanceName
Events	ASPxCallback.ClientSideEvents

Overview

Use the (ASPxClientCallback.PerformCallback) method to send a callback to the server. The (ASPxClientControlBase.InCallback) method allows you to get whether the callback is sent. Handle the (ASPxClientCallback.CallbackComplete) client event or the ASPxCallback.Callback server event to process the callback.

ASPX

<dx:ASPxCallback ID="ASPxCallback1" runat="server" ClientInstanceName="Callback1"
    OnCallback="ASPxCallback1_Callback">
    <ClientSideEvents CallbackComplete="OnCallbackComplete" />
</dx:ASPxCallback>

C#
VB.NET

protected void ASPxCallback1_Callback(object sender, CallbackEventArgs e) {
    string xpath = string.Format("//items/item[@newsID='{0}']", e.Parameter);
    XmlNode node = XmlDataSource1.GetXmlDocument().SelectSingleNode(xpath);
    if(node != null)
        e.Result = node.Attributes["Description"].Value;
}

Protected Sub ASPxCallback1_Callback(ByVal sender As Object, ByVal e As CallbackEventArgs)
    Dim xpath As String = String.Format("//items/item[@newsID='{0}']", e.Parameter)
    Dim node As XmlNode = XmlDataSource1.GetXmlDocument().SelectSingleNode(xpath)
    If node IsNot Nothing Then e.Result = node.Attributes("Description").Value
End Sub

function OnCallbackComplete(s, e) {
    var strFeedID = e.parameter.toString();
    var loadingPanel = document.getElementById("lp" + strFeedID);
    var detailsContainer = document.getElementById("details" + strFeedID);
    loadingPanel.style.display = "none";
    detailsContainer.style.display = "";
    detailsContainer.innerHTML = e.result;
}