Groovy script to save Username and Transaction date information

In Data Form, the User inputs data and saves the Form. Using the Groovy script, I want to save the Username and Transaction date in members from Plan element Dimension in the same form. The form will have a list of records, Data, Username that inputs/changes the data, and Transaction date.

It is similar like ERP system, Client wants to see the Username and Transaction date for the inputs done by User.