[spray-json] JsonFormat to process more than 22 fields

ManyFieldsJsonFormat1.scala

/*
 * case class を分割する方法
 */
import spray.json._

case class Document1(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)

case class Document2(field21: String, field22: String, field23: String, field24: String, field25: String)

case class RootDocument(doc1: Document1, doc2: Document2)

object DocumentProtocol extends DefaultJsonProtocol {

  implicit val document1Format: JsonFormat[Document1] = jsonFormat20(Document1)
  implicit val document2Format: JsonFormat[Document2]  = jsonFormat5(Document2)

  implicit object DocumentFormat extends RootJsonFormat[RootDocument] {
    override def write(obj: RootDocument): JsValue = {
      val objFields1 = obj.doc1.toJson.asJsObject.fields
      val objFields2 = obj.doc2.toJson.asJsObject.fields
      val duplicateKeys = objFields1.keySet.intersect(objFields2.keySet)
      require(duplicateKeys.isEmpty, s"duplicate key found: ${duplicateKeys}")

      JsObject(objFields1 ++ objFields2)
    }

    def read(json: JsValue): RootDocument = {
      RootDocument(json.convertTo[Document1], json.convertTo[Document2])
    }
  }
}

import DocumentProtocol._

val obj = RootDocument(
  Document1(
    "field1", "field2", "field3", "field4", "field5",
    "field6", "field7", "field8", "field9", "field10",
    "field11", "field12", "field13", "field14", "field15",
    "field16", "field17", "field18", "field19", "field20"
  ),
  Document2(
    "field21", "field22", "field23", "field24", "field25"
  )
)
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",
    |  "field25":"field25"
    |}
  """.stripMargin

println(json.parseJson.convertTo[RootDocument])

ManyFieldsJsonFormat2.scala

/*
 * case class を頑張って実装する方法
 */
import spray.json._

case class RootDocument(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, field25: String)

object DocumentProtocol extends DefaultJsonProtocol {

  implicit object DocumentFormat extends RootJsonFormat[RootDocument] {
    override def write(obj: RootDocument): JsValue = {
      JsObject(
        "field1" -> obj.field1.toJson,
        "field2" -> obj.field2.toJson,
        "field3" -> obj.field3.toJson,
        "field4" -> obj.field4.toJson,
        "field5" -> obj.field5.toJson,
        "field6" -> obj.field6.toJson,
        "field7" -> obj.field7.toJson,
        "field8" -> obj.field8.toJson,
        "field9" -> obj.field9.toJson,
        "field10" -> obj.field10.toJson,
        "field11" -> obj.field11.toJson,
        "field12" -> obj.field12.toJson,
        "field13" -> obj.field13.toJson,
        "field14" -> obj.field14.toJson,
        "field15" -> obj.field15.toJson,
        "field16" -> obj.field16.toJson,
        "field17" -> obj.field17.toJson,
        "field18" -> obj.field18.toJson,
        "field19" -> obj.field19.toJson,
        "field20" -> obj.field20.toJson,
        "field21" -> obj.field21.toJson,
        "field22" -> obj.field22.toJson,
        "field23" -> obj.field23.toJson,
        "field24" -> obj.field24.toJson,
        "field25" -> obj.field25.toJson
      )
    }

    def read(json: JsValue): RootDocument = {
      val fields = json.asJsObject.fields
      RootDocument(
        field1 = fields("field1").convertTo[String],
        field2 = fields("field2").convertTo[String],
        field3 = fields("field3").convertTo[String],
        field4 = fields("field4").convertTo[String],
        field5 = fields("field5").convertTo[String],
        field6 = fields("field6").convertTo[String],
        field7 = fields("field7").convertTo[String],
        field8 = fields("field8").convertTo[String],
        field9 = fields("field9").convertTo[String],
        field10 = fields("field10").convertTo[String],
        field11 = fields("field11").convertTo[String],
        field12 = fields("field12").convertTo[String],
        field13 = fields("field13").convertTo[String],
        field14 = fields("field14").convertTo[String],
        field15 = fields("field15").convertTo[String],
        field16 = fields("field16").convertTo[String],
        field17 = fields("field17").convertTo[String],
        field18 = fields("field18").convertTo[String],
        field19 = fields("field19").convertTo[String],
        field20 = fields("field20").convertTo[String],
        field21 = fields("field21").convertTo[String],
        field22 = fields("field22").convertTo[String],
        field23 = fields("field23").convertTo[String],
        field24 = fields("field24").convertTo[String],
        field25 = fields("field25").convertTo[String]
      )
    }
  }
}

import DocumentProtocol._

val obj = RootDocument(
  "field1", "field2", "field3", "field4", "field5",
  "field6", "field7", "field8", "field9", "field10",
  "field11", "field12", "field13", "field14", "field15",
  "field16", "field17", "field18", "field19", "field20",
  "field21", "field22", "field23", "field24", "field25"
)
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",
    |  "field25":"field25"
    |}
  """.stripMargin

println(json.parseJson.convertTo[RootDocument])