Question

我正在尝试为案例类编写一个读/写值，其中许多值可能为null。按照Play Framework的教程，我将其写为

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，由于“应用程序不接受参数”，因此提升方法不起作用。

案例类是

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)

}

其他案例类

也会发生同样的事情

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 _)
}

我写了读写值，但省略了它们以节省空间。

非常感谢任何和所有帮助。

Answer 1

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Reads OSBatchStatus的定义假定所有字段都是可选字段，因此您的案例类应如下所示：

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

相同的规则适用于您的IncomingMessage案例类（四个字段是强制性的，其他字段应为Option[T]）。此外，由于JSON文件中的字段与案例类中的字段具有完全相同的名称，因此您可以使用将为您自动生成Reads/Writes/Format的play-json方法：

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`

JSON读/写错误：应用程序不接受参数

1 个答案: