How to reference a Grails domain class fields from outside of the Grails controller and view?

class Child {
    static hasMany = [ toys : Toy ]
    String name
    Set  toys
}
class Toy {
    static belongsTo = [ owner : Child ]
    String name
}

child = Child.findByName("Joe")

child = Child.findById(123)

child.getToys()

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: Child.toys, no session or session was closed

child = Child.findByName("Joe", [ fetch: [ toys: 'eager' ] ] )