ASPxCallback Class

A non-visual component that allows you to make a round trip to the server (send a custom callback request) and perform server-side actions. The component cannot update other controls in a callback.

Namespace: DevExpress.Web

Assembly: DevExpress.Web.v24.2.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.

Run Demo

Create a Callback Control

Design Time

The ASPxCallback control is available on the DX.24.2: Components toolbox tab in the Microsoft Visual Studio IDE.

Callback Control

Drag the control onto a form and customize the control’s 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

Note

DevExpress controls require that you register special modules, handlers, and options in the Web.config file. You can change this file or switch to the Design tab in the Microsoft Visual Studio IDE to automatically update the Web.config file. Note that this information is automatically registered if you use the DevExpress Template Gallery to create a project.

Client-Side API

Availability	Available by default.
Client object type	ASPxClientCallback
Access name	ASPxCallback.ClientInstanceName
Events	ASPxCallback.ClientSideEvents

Overview

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

You can use the JSProperties property to send information from the server to the client.

ASPX

<dx:ASPxButton ID="ASPxButton1" runat="server" Text="Get time from server" AutoPostBack="False">
    <ClientSideEvents Click="function(s, e) { callbackControl.PerformCallback(); }" />
</dx:ASPxButton>

<dx:ASPxCallback ID="ASPxCallback1" runat="server" ClientInstanceName="callbackControl" 
    OnCallback="ASPxCallback1_Callback">
    <ClientSideEvents CallbackComplete="function(s, e) {
        document.getElementById('editorContainer').innerHTML = s.cpTextBox1;
        textBox2.SetText(s.cpTime);
    }" />
</dx:ASPxCallback>

<table id="formContainer">
    <tr>
        <td id="editorContainer">
            <asp:TextBox ID="TextBox1" runat="server" Width="200px" ></asp:TextBox>
        </td>
        <td>
            <dx:ASPxTextBox ID="ASPxTextBox1" runat="server" ClientInstanceName="textBox2" Width="200px" />
        </td>
    </tr>
</table>

C#
VB.NET

protected void ASPxCallback1_Callback(object source, DevExpress.Web.ASPxCallback.CallbackEventArgs e){
    ASPxCallback callbackControl = source as ASPxCallback;
    string time = DateTime.Now.ToString("T");
    TextBox1.Text = time;
    callbackControl.JSProperties["cpTextBox1"] = ASPxCallback.GetRenderResult(TextBox1);
    callbackControl.JSProperties["cpTime"] = time;
}

Protected Sub ASPxCallback1_Callback(ByVal source As Object, ByVal e As DevExpress.Web.ASPxCallback.CallbackEventArgs)
    Dim callbackControl As ASPxCallback = TryCast(source, ASPxCallback)
    Dim time As String = DateTime.Now.ToString("T")
    TextBox1.Text = time
    callbackControl.JSProperties("cpTextBox1") = ASPxCallback.GetRenderResult(TextBox1)
    callbackControl.JSProperties("cpTime") = time
End Sub