Adding common methods to Grails domain objects

If you don't want to change your domain hierarchy, but need to add common function to multiple domains without copy/paste, one simple option is to create and implement trait. For example:

class Test implements LogTrait {
  String name
}

trait LogTrait {
  def springSecurityService

  def afterInsert() {
    log.info(this as JSON)
  }
}

Nice bonus is that events and injected services work just fine as it would be in original class.