Form Data source Modified field in D365

public static class InventTransferOrders_Extension

{

    /// <summary>

    /// Assign Barcode based on Item Id

    /// </summary>

    /// <param name="sender">

    /// </param>

    /// <param name="e">

    /// </param>

    

    [FormDataFieldEventHandler(formDataFieldStr(InventTransferOrders, InventTransferLine, ItemId), FormDataFieldEventType::Modified)]

    public static void ItemId_OnModified(FormDataObject sender, FormDataFieldEventArgs e)

    {

        FormDataSource          inventTransferLine_ds   = sender.datasource();

        InventTransferLine      inventTransferLine      = inventTransferLine_ds.cursor();

        InventDim               inventDim;

        InventItemBarcode       inventItemBarcode;

        inventDim           = InventDim::find(inventTransferLine.InventDimId);

        inventItemBarcode   = InventItemBarcode::findPurchBarcodeDimension(inventTransferLine.ItemId, inventDim, '', InventTableModule::find(inventTransferLine.ItemId, ModuleInventPurchSales::Invent).UnitId);

        if (!inventItemBarcode.RecId)

        {

            inventItemBarcode = InventItemBarcode::findPurchBarcodeDimension(inventTransferLine.ItemId, inventDim);

        }

        inventTransferLine.BarCode = inventItemBarcode.ItemBarCode;  //custom field

    }

}