Hello Sachin,

By design, InvokeCommandAction executes a specified ICommand on a specific target object when invoked. Via this ICommand the DraggedGroupByCommandExecute event can be triggered.

public class DropCommand : ICommand
    {
        public event EventHandler CanExecuteChanged;

        public bool CanExecute(object parameter)
        {
            return true;
        }

        public void Execute(object parameter)
        {
            DraggedGroupByCommandExecute(parameter);
        }
        private void DraggedGroupByCommandExecute(object parameter)
        {
  
                 //...TO DO
            
        }

    }

This command can be called in the Grouped event handler. In this handler we can get reference to the GroupEventArgs ,where we have information about all grouped columns.

private void DataGrid_Grouped(object sender, Infragistics.Windows.DataPresenter.Events.GroupedEventArgs e)
        {
            MyCommand = new DropCommand();        
            MyCommand.Execute(e);
        }

When passed to the DraggedGroupByCommandExecute method we can obtain the collection with grouped columns via the Gropus property of the event argument and each column can be accessed by index. For example:

private void DraggedGroupByCommandExecute(object parameter)
        {

            Infragistics.Windows.DataPresenter.Events.GroupedEventArgs param = parameter as Infragistics.Windows.DataPresenter.Events.GroupedEventArgs;           
            var data = param.Groups;

            int index = data.Length - 1;
            string LastGrouped = data[index].FieldName; 
            MessageBox.Show(LastGrouped);
            
        }