Grails controllers dynamic finders

Question

I'm kinda new to Grails so I need help with this matter. Imagine I have these classes:

Class User{
String name
String nr

}

class Computer{

String processor
String ram
User user
}

Class Room{
String roomNr
Computer computer
}

I want to do a controller like this:

def print= {

        def user = User.get(1)

        def computer = Computer.findAllByUser(user) // all computers filtered by User

        [computer: computer]       
    }

The controller works good, but I want to be able to pass not only the computer instances, but also the Room's with that computer id's. I dont know how to do it, but would be something like this (same controller, same action):

def print= {

        def user = User.get(1)

        def computer = Computer.findAllByUser(user) // all computers filtered by User
        def room = Room.findAllByComputer(computer) ##

        [computer: computer]       
    }

Well, this is wrong because, where the ### is, 'computer' represents a list of id's and not a single id. As I am passing a list of computers to be printed in my gsp inside a g: each tag like this: (it. Processor, it. Ram). I dont know how to get all the rooms which are using the current computer in the each tag. This is a bit hard to explain, but basically my output would be:

<g:each in="${computer}"
Computer1:
Processor: ${it.processor}
Ram: ${it.ram}
Room: ????? (How to get here??)
</g:each>

Answer 1

I came up with something like this, but I didn't test it.

Controller:

def print = {

  def user = User.get(1)
  def computer = Computer.findAllByUser(user)
  def rooms = [:]

  // get rooms for that computer
  computer.each{

    def computerRooms = Room.findAllByComputer(it) // find all rooms where current computer is
    rooms.put(it.id, computerRooms) // map all the rooms with computer id

  }

  [computer: computer, rooms: rooms]      
}

View:

<g:each in="${computer}">
  Computer1:
  Processor: ${it.processor}
  Ram: ${it.ram}
  Rooms: <g:join in="${rooms[it.id]}" delimiter=", "/>
</g:each>

Rooms map uses computer id as a key and list of all rooms where that computer is as value. Of course If I understood you correctly ;)

EDIT

If you need access room details, you can replace join tag with another each tag, like this:

<g:each in="${computer}" >
  Computer1:
  Processor: ${it.processor}
  Ram: ${it.ram}
  Rooms: <br/>
  <g:each in="${rooms[it.id]}">
    Room id: ${it.id}
    Room number: ${it.number}
  </g:each>
</g:each>

And you can also implement the Room class toString() method, because join tag uses it to render text:

Class Room{
  String roomNr
  ...

  String toString(){
    roomNr
  }
}

Now when you use join tag on list of Room class instances, it will print room number.