JSON读/写错误：应用程序不接受参数

我正在尝试为一个case类编写一个读/写值，其中许多值可能为null。根据Play框架的教程，我将其编写为

implicit val incomingMessageWrites: Writes[IncomingMessage] = (
        (JsPath \ "stageNum").write[Int] and
        (JsPath \ "stage").write[String] and
        (JsPath \ "stageTime").write[Long] and
        (JsPath \ "vendorId").write[String] and
        (JsPath \ "text").writeNullable[String] and
        (JsPath \ "campaignCode").writeNullable[String] and
        (JsPath \ "osTotals").writeNullable[OSTotals] and
        (JsPath \ "splitSegment").writeNullable[Int] and
        (JsPath \ "segmentNum").writeNullable[Int] and
        (JsPath \ "osBatchStatus").writeNullable[OSBatchStatus]
    )(unlift(IncomingMessage.unapply))

然而，我一直遇到同样的问题，IntelliJ告诉我提升方法不起作用，因为“应用程序不接受参数”

这方面的case类是

case class IncomingMessage(
  stageNum: Int,
  stage: String,
  stageTime: Long,
  vendorId: String,
  text: String,
  campaignCode: String,
  osTotals: OSTotals,
  splitSegment: Int,
  segmentNum: Int,
  osBatchStatus: OSBatchStatus) {

    def this(stageNum: Int, stage: String, stageTime: Long, vendorId: String, text: String, campaignCode: String) =
      this(stageNum, stage, stageTime, vendorId, text, campaignCode, null, 0, 0, null)

    def this(stageNum: Int, stage: String, stageTime: Long, splitSegment: Int, vendorId: String, text: String, campaignCode: String) =
      this(stageNum, stage, stageTime, vendorId, text, campaignCode, null, splitSegment, 0, null)

    def this(stageNum: Int, stage: String, stageTime: Long, segmentNum: Int, vendorId: String) =
      this(stageNum, stage, stageTime, vendorId, null, null, null, 0, segmentNum, null)

    def this(stageNum: Int, stage: String, stageTime: Long, segmentNum: Int, vendorId: String, osTotals: OSTotals) =
      this(stageNum, stage, stageTime, vendorId, null, null, osTotals, 0, segmentNum, null)

    def this(stageNum: Int, stage: String, stageTime: Long, vendorId: String, oSBatchStatus: OSBatchStatus) =
      this(stageNum, stage, stageTime, vendorId, null, null, null, 0, 0, osBatchStatus)

}

另一个case类也会发生同样的情况

case class OSBatchStatus(os: String, success: Int, failure: Int)

object OSBatchStatus {
  implicit val oSBatchStatusReads: Reads[OSBatchStatus] = (
    (JsPath \ "os").readNullable[String] and
      (JsPath \ "success").readNullable[Int] and
      (JsPath \ "failure").readNullable[Int]
    )(OSBatchStatus.apply _)
}

我编写了读写值，但为了节省空间，省略了它们

---

我们将非常感谢您的任何帮助

如果输入JSON文件中有可选字段，那么案例类的相应字段也应该是可选的。您对

的定义为
OSBatchStatus
的定义假定所有字段都是可选的，因此您的case类应该如下所示：

case class OSBatchStatus(os: Option[String], success: Option[Int], failure: Option[Int])

同样的规则也适用于您的
IncomingMessage
案例类（四个字段是必需的，每隔一个字段应该是
选项[T]
）。此外，由于JSON文件中的字段与case类中的字段具有完全相同的名称，因此可以使用play JSON方法为您自动生成
Reads/Writes/Format
：

import play.api.libs.functional.syntax._
import play.api.libs.json._

implicit val incomingMessageWrites = Json.writes[IncomingMessage]
implicit val osBatchStatusReads    = Json.reads[OSBatchStatus]
implicit val osTotalsFormat        = Json.format[OSTotals] // Will generate both `Reads` and `Writes`

这解决了我的问题。非常感谢。