spray-json handle more than 22 fields

Connect.scala

import spray.json.{DefaultJsonProtocol, JsBoolean, JsObject, JsString, JsValue, RootJsonFormat}

case class Document(field1: String, field2: String, field3: String, field4: String, field5: String, field6: String,
                    field7: String, field8: String, field9: String, field10: String, field11: String, field12: String,
                    field13: String, field14: String, field15: String, field16: String, field17: String, field18: String,
                    field19: String, field20: String, field21: String, field22: String, field23: String, field24: String,
                    approved: Boolean)

object DocumentProtocol extends DefaultJsonProtocol {

  implicit object DocumentFormat extends RootJsonFormat[Document] {
    override def write(obj: Document): JsValue = {
      JsObject(
        "field1" -> JsString(obj.field1),
        "field2" -> JsString(obj.field2),
        "field3" -> JsString(obj.field3),
        "field4" -> JsString(obj.field4),
        "field5" -> JsString(obj.field5),
        "field6" -> JsString(obj.field6),
        "field7" -> JsString(obj.field7),
        "field8" -> JsString(obj.field8),
        "field9" -> JsString(obj.field9),
        "field10" -> JsString(obj.field10),
        "field11" -> JsString(obj.field11),
        "field12" -> JsString(obj.field12),
        "field13" -> JsString(obj.field13),
        "field14" -> JsString(obj.field14),
        "field15" -> JsString(obj.field15),
        "field16" -> JsString(obj.field16),
        "field17" -> JsString(obj.field17),
        "field18" -> JsString(obj.field18),
        "field19" -> JsString(obj.field19),
        "field20" -> JsString(obj.field20),
        "field21" -> JsString(obj.field21),
        "field22" -> JsString(obj.field22),
        "field23" -> JsString(obj.field23),
        "field24" -> JsString(obj.field24),
        "approved" -> JsBoolean(obj.approved)
      )
    }

    def read(json: JsValue): Document = {
      val fields = json.asJsObject.fields
      Document(
        fields("field1").convertTo[String],
        fields("field2").convertTo[String],
        fields("field3").convertTo[String],
        fields("field4").convertTo[String],
        fields("field5").convertTo[String],
        fields("field6").convertTo[String],
        fields("field7").convertTo[String],
        fields("field8").convertTo[String],
        fields("field9").convertTo[String],
        fields("field10").convertTo[String],
        fields("field11").convertTo[String],
        fields("field12").convertTo[String],
        fields("field13").convertTo[String],
        fields("field14").convertTo[String],
        fields("field15").convertTo[String],
        fields("field16").convertTo[String],
        fields("field17").convertTo[String],
        fields("field18").convertTo[String],
        fields("field19").convertTo[String],
        fields("field20").convertTo[String],
        fields("field21").convertTo[String],
        fields("field22").convertTo[String],
        fields("field23").convertTo[String],
        fields("field24").convertTo[String],
        fields("approved").convertTo[Boolean]
      )
    }
  }

}

/**
  * Handle objects more than 22 fields
  */
def handleDocument(): Unit = {
  import DocumentProtocol._
  val obj = Document(
    "field1", "field2", "field3", "field4", "field5", "field6",
    "field7", "field8", "field9", "field10", "field11", "field12",
    "field13", "field14", "field15", "field16", "field17", "field18",
    "field19", "field20", "field21", "field22", "field23", "field24",
    approved = true
  )
  println(obj.toJson.toString())

  val json =
    """
      |{
      |  "field1":"field1",
      |  "field2":"field2",
      |  "field3":"field3",
      |  "field4":"field4",
      |  "field5":"field5",
      |  "field6":"field6",
      |  "field7":"field7",
      |  "field8":"field8",
      |  "field9":"field9",
      |  "field10":"field10",
      |  "field11":"field11",
      |  "field12":"field12",
      |  "field13":"field13",
      |  "field14":"field14",
      |  "field15":"field15",
      |  "field16":"field16",
      |  "field17":"field17",
      |  "field18":"field18",
      |  "field19":"field19",
      |  "field20":"field20",
      |  "field21":"field21",
      |  "field22":"field22",
      |  "field23":"field23",
      |  "field24":"field24",
      |  "approved":true
      |}
    """.stripMargin
  println(json.parseJson.convertTo[Document])
}

/*
 * output
Document(field1,field2,field3,field4,field5,field6,field7,field8,field9,field10,field11,field12,field13,field14,field15,field16,field17,field18,field19,field20,field21,field22,field23,field24,true)
*/