D365 Form data field event handler

Hi,

I am using form data field event handler. Here how can i call data source methods and form methods. please suggest me.
/// <summary>
///
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
[FormDataFieldEventHandler(formDataFieldStr(PurchTable, PurchLine, itemBarCode), FormDataFieldEventType::Modified)]
public static void itemBarCode_OnModified(FormDataObject sender, FormDataFieldEventArgs e)
{
FormDataSource purchLine_ds = sender.datasource();
PurchLine purchLine = purchLine_ds.cursor();

}

Thanks,