Mapping oneToMany relationship

gistfile1.scala

case class Music(id:ID, title:String, isrc:String)

case class Compilation(id:ID=None, title:String, musics: List[Music], author:User /* TODO Either[DJ,Programmer]? */)
case class User(id:ID=None, name:String, email:String, password:String)

  object Musics extends Table[Music]("music")  {
    def id = this.autoIncPk("id") 
    def title = this.string("title")
    def isrc = this.string("isrc")

    def * = id.? ~ title ~ isrc <> (Music, Music.unapply _) 
    def autoInc = title ~ isrc returning id
  }

  object Users extends Table[User]("user") {
    def id = this.autoIncPk("id")
    def name = this.string("name")
    def email = this.string("email")
    def password = this.string("password")
    def * = id.? ~ name ~ email ~ password <> (User, User.unapply _)
  } /* TODO all the other fields */

  object CompiledMusics extends Table[(Int, Int)]("compiled_music") {
    def musicId = column[Int]("music_id")
    def compilationId = column[Int]("compilation_id")
    def musics = foreignKey(tableName+"_music_fk", musicId, Musics)(_.id)
    def compilations = foreignKey(tableName+"_compilation_fk", compilationId, Compilations)(_.id)
    def * = musicId ~ compilationId
  }
  
  object Compilations extends Table[Compilation]("compilation") {
    def id = this.autoIncPk("id")
    def title = this.string("title")
    def authorId = column[Int]("author_id")
    def authorFk = foreignKey(tableName+"_author_fk", authorId, Users)(_.id)
    def musics = 
      for( cm <- CompiledMusics; if cm.compilationId === id; m <- cm.musics; if m.id === cm.musicId) yield m
    def author = for(a <- Users; if a.id === authorId) yield a
    /* How it should be
    def * = id.? ~ title ~ musics ~ author  <>
    		(Compilation, x => Compilation.unapply(x) map { x => (x._1,x._2) } ) 
    */
    /* TODO ugly cheating/hacking to workaround my doubts regarding foreign keys! */
    def * = id.? ~ title   <>  
    		(Compilation(_,_,List(),null), x => Compilation.unapply(x) map { x => (x._1,x._2) } ) 
  }