Add constraints to the elemets of List

[MaxR]

Is there are any possible way to add constraints to the elements of List? For example I have a command which accept List and I want add constraints on this elements, for example on size.

class SongCommand {

    String title
    List<String> couplet
    List<String> chorus
    Boolean isChorus
    Boolean isChorusRepeat

    static constraints = {
        title(blank: false, maxSize: 6)
        isChorus(blank: true)
    }

}

How to do that?

Thank you.

 

[MaxR]

I have the solution

static constraints = {
  couplet(validator: { val ->
    boolean isValid = true 
    val.each {
      if (it.size() < 3) isValid = false
    } 

    return isValid
  })
}

It's not final, but as example. Better return error code message, not true/false.

 

[dave]

Thanks for posting your solution.