结果json对象与spray-json不符合预期

Question

我有这样的模型来解析db到json的结果在休息时api与akka-http

case class Category(id: Long,
                    title: String,
                    slug: String,
                    image: String,
                    parentId: Long,
                    createdAt: Timestamp) extends BaseEntity

object Category extends DefaultJsonProtocol with SprayJsonSupport {

  implicit object TimestampFormat extends RootJsonFormat[Timestamp] {
    val format = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss")

    def write(obj: Timestamp) = JsString(format.format(obj.getTime))

    def read(json: JsValue) = json match {
      case JsString(s) => new Timestamp(format.parse(s).getTime)
      case _ => throw DeserializationException("Date expected")
    }
  }

  implicit object ObjectJsonFormat extends RootJsonFormat[Category] {
    val format = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss")

    def write(obj: Category) = JsObject(Map(
      "id" -> JsNumber(obj.id),
      "title" -> JsString(obj.title),
      "slug" -> JsString(obj.slug),
      "image" -> JsString(obj.image),
      "parentId" -> JsNumber(obj.parentId),
      "createdAt" -> JsString(format.format(obj.createdAt.getTime))
    ))

    def read(value: JsValue): Category = value.convertTo[Category]
  }

  implicit val objectFormat = jsonFormat6(Category.apply)
}

case class CategoryResponse(status: Int, result: Category)

object CategoryResponse extends DefaultJsonProtocol with SprayJsonSupport {
  implicit val objectFormat = jsonFormat2(CategoryResponse.apply)
}

但是如果case类的成员数超过4，则json对象的位置成员与case类的位置不一样。结果就像这样

{
  "status": 1,
  "result": {
    "image": "https://yt3.ggpht.com/-Fq_uiT7y10k/AAAAAAAAAAI/AAAAAAAAAAA/YzIf8sfr7sI/s88-c-k-no-mo-rj-c0xffffff/photo.jpg",
    "slug": "news",
    "id": 3,
    "createdAt": "2016-11-23 14:09:45",
    "title": "news",
    "parentId": 1
  }
}

如何像这样设置位置成员json对象

{
      "status": 1,
      "result": {
        "id": 3,
        "title": "news",
        "slug": "news",
        "image": "https://yt3.ggpht.com/-Fq_uiT7y10k/AAAAAAAAAAI/AAAAAAAAAAA/YzIf8sfr7sI/s88-c-k-no-mo-rj-c0xffffff/photo.jpg",
        "parentId": 1,
        "createdAt": "2016-11-23 14:09:45"
      }
    }