Tab
A newer version of this page is available. Switch to the current version.

ASPxListBox.Callback Event

Fires when a round trip to the server has been initiated by a call to the client ASPxClientListBox.PerformCallback method.

Namespace: DevExpress.Web

Assembly: DevExpress.Web.v18.2.dll

Declaration

public event CallbackEventHandlerBase Callback
Public Event Callback As CallbackEventHandlerBase

Event Data

The Callback event's data class is CallbackEventArgsBase. The following properties provide information specific to this event:

Property Description
Parameter Gets a string that contains specific information (if any) passed from the client side.

Remarks

The Callback event allows any desired server-side processing to be performed in response to a call to the client ASPxClientListBox.PerformCallback method, and the editor's content being updated, as required.

Specific information passed from the client side can be obtained via the CallbackEventArgsBase.Parameter property.

Note that the necessary actions can be additionally performed on the client side before and after callback processing by using the ASPxClientListBox.BeginCallback and ASPxClientListBox.EndCallback client event.

NOTE

The ASPxListBox control allows you to modify the ASPxListEdit.Items collection on callbacks only (e.g. add and remove items, populate the controls with new data from a data source, etc.).

It is not possible, for example, to modify a column collection, change items selection, or change SelectionMode on callbacks. To perform these actions on the client side, you can wrap the control with the ASPxCallbackPanel control and process a required scenario on a callback to the panel.

Examples

This part of the Multiple Selection demo illustrates how to use multi-selection mode for the ASPxListBox editor.

 ...
     protected void lbModels_Callback(object sender, DevExpress.Web.CallbackEventArgsBase e) {
         FilterModels(lbFeatures.Items);
         lbModels.DataBind();
     }
     protected void FilterModels(ListEditItemCollection items) {
     ...     
     }
...
See Also