Serialize and deserialize case classes with helper object

SerializedIdentifierKey.scala

case class IdentifierKey(idType: String, id: String) {
  override def toString: String = SerializedIdentifierKey(this)
}

object SerializedIdentifierKey extends (IdentifierKey => String) {
  val delimiter = ':'

  def apply(i: IdentifierKey): String = i.idType + SerializedIdentifierKey.delimiter + i.id

  def unapply(s: String): Option[IdentifierKey] = {
    val Array(idType, id) = s.split(SerializedIdentifierKey.delimiter)
    Some(IdentifierKey(idType, id))
  }
}