Play2 Scala：将Json反序列化为对象列表

Question

我正在尝试将使用Play的WSClient的json身体反应反序列化为一个对象列表，我认为我距离成功并不太近，但可能最后一块拼图错过了我。

这些是必须将传入的json反序列化的case类（及其伴随对象）。

EmployerStoreDTO：

import play.api.libs.json._

case class EmployerStoreDTO (id: String, storeName: String)

object EmployerStoreDTO {
  implicit val reads: Reads[EmployerStoreDTO] = Json.reads[EmployerStoreDTO]

  implicit val employerStoreDTOlistReads: Reads[List[EmployerStoreDTO]] = Reads.list[EmployerStoreDTO]
}

CompanyEmployerDTO：

import java.time.DayOfWeek

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

case class CompanyEmployerDTO(id: String,
                              companyName: String,
                              companyUrl: Option[String],
                              description: Option[String],
                              startDayOfWeek: DayOfWeek,
                              logoUrl: Option[String],
                              stores: List[EmployerStoreDTO] = List(),
                              supportHelpText: Option[String],
                              themeId: Option[String]) {
}

object CompanyEmployerDTO {

  import model.EmployerStoreDTO._

  implicit val startDayOfWeekReads: Reads[DayOfWeek] = (JsPath \ "weekStartDay").read[Int].map(DayOfWeek.of)

  implicit val reads: Reads[CompanyEmployerDTO] = (
    (JsPath \ "id").read[String] and
      (JsPath \ "companyName").read[String] and
      (JsPath \ "companyUrl").readNullable[String] and
      (JsPath \ "description").readNullable[String] and startDayOfWeekReads and
      (JsPath \ "logoUrl").readNullable[String] and employerStoreDTOlistReads and
      (JsPath \ "supportHelpText").readNullable[String] and
      (JsPath \ "themeId").readNullable[String]
    ) (CompanyEmployerDTO.apply _)

  implicit val companyEmployerDTOListReads: Reads[List[CompanyEmployerDTO]] = Reads.list[CompanyEmployerDTO]
}

CompanyEmployerCollectionDTO：

import play.api.libs.json.Reads._
import play.api.libs.json._

case class CompanyEmployerCollectionDTO (companies: List[CompanyEmployerDTO])

object CompanyEmployerCollectionDTO {

  implicit val reads: Reads[CompanyEmployerCollectionDTO] =
    (JsPath \ "companies").read[List[CompanyEmployerDTO]].map(CompanyEmployerCollectionDTO.apply)

}

我看到有效载荷是由我的WsClient：收到的

但正如我试图将响应反序列化如下：response.json.as[CompanyEmployerCollectionDTO]

我收到此错误：

Caused by: play.api.libs.json.JsResultException: JsResultException(errors:List((/companies(0),List(JsonValidationError(List(error.expected.jsarray),WrappedArray())))))
    at play.api.libs.json.JsReadable.$anonfun$as$2(JsReadable.scala:25)
    at play.api.libs.json.JsError.fold(JsResult.scala:64)
    at play.api.libs.json.JsReadable.as(JsReadable.scala:24)
    at play.api.libs.json.JsReadable.as$(JsReadable.scala:23)
    at play.api.libs.json.JsObject.as(JsValue.scala:124)
    at services.com.mycompany.ApiEmployeeClient.$anonfun$callGetEmployers$2(ApiEmployeeClient.scala:33)
    at scala.util.Success.$anonfun$map$1(Try.scala:255)
    at scala.util.Success.map(Try.scala:213)
    at scala.concurrent.Future.$anonfun$map$1(Future.scala:292)
    at scala.concurrent.impl.Promise.liftedTree1$1(Promise.scala:33)

Answer 1

问题是裸and employerStoreDTOlistReads。因为您没有指定路径（与其他CompanyEmployerDTO成员一样），解码器将尝试将当前JSON值本身（表示CompanyEmployerDTO的对象）解码为EmployerStoreDTO列表。

用and (JsPath \ "stores").read[List[EmployerStoreDTO]]替换这两个单词应该修复你的代码，但是对于它的价值你也可以通过废弃List实例（将自动提供），删除导入等来简化你的实现。

import play.api.libs.json._

case class EmployerStoreDTO (id: String, storeName: String)

object EmployerStoreDTO {
  implicit val reads: Reads[EmployerStoreDTO] = Json.reads[EmployerStoreDTO]
}

import java.time.DayOfWeek

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

case class CompanyEmployerDTO(id: String,
                              companyName: String,
                              companyUrl: Option[String],
                              description: Option[String],
                              startDayOfWeek: DayOfWeek,
                              logoUrl: Option[String],
                              stores: List[EmployerStoreDTO] = List(),
                              supportHelpText: Option[String],
                              themeId: Option[String]) {
}

object CompanyEmployerDTO {
  implicit val reads: Reads[CompanyEmployerDTO] = (
    (JsPath \ "id").read[String] and
      (JsPath \ "companyName").read[String] and
      (JsPath \ "companyUrl").readNullable[String] and
      (JsPath \ "description").readNullable[String] and
      (JsPath \ "weekStartDay").read[Int].map(DayOfWeek.of) and
      (JsPath \ "logoUrl").readNullable[String] and
      (JsPath \ "stores").read[List[EmployerStoreDTO]] and
      (JsPath \ "supportHelpText").readNullable[String] and
      (JsPath \ "themeId").readNullable[String]
    ) (CompanyEmployerDTO.apply _)
}

import play.api.libs.json.Reads._
import play.api.libs.json._

case class CompanyEmployerCollectionDTO (companies: List[CompanyEmployerDTO])

object CompanyEmployerCollectionDTO {
  implicit val reads: Reads[CompanyEmployerCollectionDTO] =
    (JsPath \ "companies").read[List[CompanyEmployerDTO]].map(CompanyEmployerCollectionDTO.apply)
}

这将与您的代码完全相同，但更简洁，更易于管理。