import java.text.SimpleDateFormat class TaskModification { Person person TaskModificationType taskModificationType Task task Date date = new Date() String comment = "" static belongsTo = [Person, TaskModificationType, Task] static constraints = { person() taskModificationType() task() date() comment() } String toString() { def date = new SimpleDateFormat("EEE, dd-MMM-yyyy").format(this.date) "${taskModificationType} on ${date} by ${person}." } }