How to: Obtain Server Data From the Client

• Dec 17, 2020

This example shows how to display the number of selected nodes. The client-side ASPxClientTreeList.SelectionChanged event is handled to send a callback to the server to obtain the number of selected nodes. This information is set to the client (ASPxClientTreeList.CustomDataCallback event) and displayed below the ASPxTreeList.

The image below shows the result:

C#

protected void ASPxTreeList1_CustomDataCallback(object sender,
DevExpress.Web.ASPxTreeList.TreeListCustomDataCallbackEventArgs e) {
    e.Result = ASPxTreeList1.SelectionCount.ToString();
}

ASPX

<ClientSideEvents CustomDataCallback="function(s, e) {
    document.getElementById('lbSelectionInfo').innerHTML = e.result;
}"

SelectionChanged="function(s, e) {
    treeList.PerformCustomDataCallback('');
}" />