JSON Read/Write Error: Application Does Not Take Parameters

Question

我正在尝试为一个案例 class 编写一个 Read/Write 值，其中许多值可能为空。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))

但是，我一直遇到同样的问题，IntelliJ 告诉我提升方法不起作用，因为 "Application Does Not Take Parameters"。

案例 class 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)

}

另一种情况也是如此class

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 _)
}

我写了读取和写入值，但为了保存而省略了它们 space。

我们将不胜感激任何帮助。

Answer 1

如果您的输入 JSON 文件中有可选字段，那么您的案例 class 的相应字段也应该是可选的。您为 OSBatchStatus 定义的 Reads 假定所有字段都是可选的，因此您的案例 class 应该如下所示：

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

同样的规则适用于您的 IncomingMessage 案例 class（四个字段是必填字段，其他字段应该是一个 Option[T]）。此外，由于 JSON 文件中的字段与案例 class 中的字段名称完全相同，您可以使用 play-json 方法自动生成 Reads/Writes/Format你：

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 Read/Write Error: Application Does Not Take Parameters

JSON Read/Write Error: Application Does Not Take Parameters

json

scala

playframework-2.0