spray-json format and spray-httpx FromStringDeserializer for Java UUIDs

UUIDMarshalling.scala

import java.util.UUID

import spray.httpx.unmarshalling.{FromStringDeserializer, MalformedContent}

object UUIDMarshalling {

  import spray.json._

  implicit object UUIDJsonFormat extends JsonFormat[UUID] {

    def write(uuid: UUID): JsValue = JsString(uuid.toString)

    def read(json: JsValue): UUID = json match {

      case JsString(uuidToken) => parseUuidString(uuidToken) match {
        case None => deserializationError(s"Expected UUID format, got $uuidToken")
        case Some(uuid) => uuid
      }

      case unknown => deserializationError(s"Expected JsString, got $unknown")
    }
  }

  implicit val UUIDFromStringDeserializer = new FromStringDeserializer[UUID] {

    override def apply(uuidString : String) = parseUuidString(uuidString) match {
      case Some(uuid) => Right(uuid)
      case None => Left(MalformedContent(s"Could not parse UUID: $uuidString"))
    }
  }

  private def parseUuidString(token: String): Option[UUID] = {
    if (token.length != 36) None
    else try Some(UUID.fromString(token))
    catch {
      case p: IllegalArgumentException => return None
    }
  }
}