Rules about relationships in a Domain Object

Question

Is there such of a constraint that can validate relationships in a Domain object?

For example if you had a Meeting object with Participants and an Organization. Is there a way that you could make the Meeting contain a constraint that the Participants were a member of the Organization object?

Answer 1

Besides the fact you can author your own types of constraints, you also have the ability to write your own validation routines using validator. The Grails documentation covers a lot of the details but a quick example would be:

class Meeting {
  static belongsTo = [org: Orginization]
  static hasMany = [partcipants: Person]
  ...
  static constraints {
    org(validator: {val, obj ->
      if (obj.partcipants.find{ it.org.id != val.id }) return 'some.message.code'
    })
  }
  ...
}

Keep in mind the above is off the top of my head (and I have a head cold) but it should point you in the right direction.