使用Circe解码对象的集合

Question

我有两门课看起来就像这样

import io.circe.Decoder

case class FactResponse(id: String, status: String) {
  ...
}


object FactResponse {

  implicit val decoder: Decoder[FactResponse] =
    Decoder.forProduct2("id", "status")(FactResponse.apply)

  def apply(json: String): FactResponse = {
    import io.circe.parser.decode
    decode[FactResponse](json).right.get
  }
}    



case class RuleEngineRequestResponse(content: Seq[Map[String, String]])

object RuleEngineRequestResponse {

  implicit val decoder: Decoder[RuleEngineRequestResponse] =
    Decoder.forProduct1("content")(RuleEngineRequestResponse.apply(_: String))

  def apply(json: String): RuleEngineRequestResponse = {
    import io.circe.parser.decode
    println("here")
    print(json)
    println(decode[RuleEngineRequestResponse](json).left.get)
    decode[RuleEngineRequestResponse](json).right.get
  }
}

我正试图解码一个类似于这样的json

{“内容”:{"id":"22"，“状态”：“22”}

但是，我的解码失败是DecodingFailure(字符串，下行域(“内容”))

我不知道这里到底出了什么问题，json肯定是正确的，我甚至试图将内容解析成一系列的映射，但是，我还是一次又一次地得到了相同的东西。知道如何使用circe将嵌套对象解析为数组吗？

Answer 1

我认为，如果让circe自动导出解码器，可以大大简化解码过程：

import io.circe.generic.auto._
import io.circe.parser.decode

case class FactResponse(id: String, status: String)
case class RuleEngineRequestResponse(content: Seq[FactResponse])

object Sample extends App {
  val testData1 =
    """
      |{
      |   "content":[
      |      {
      |         "id":"22",
      |         "status":"22"
      |      }
      |   ]
      |}""".stripMargin

  val testData2 =
    """
      |{
      |   "content":[
      |      {
      |         "id":"22",
      |         "status":"22"
      |      },
      |      {
      |         "id":"45",
      |         "status":"56"
      |      }
      |   ]
      |}""".stripMargin

  println(decode[RuleEngineRequestResponse](testData1))
  println(decode[RuleEngineRequestResponse](testData2))

}

这一产出如下：

Right(RuleEngineRequestResponse(List(FactResponse(22,22))))
Right(RuleEngineRequestResponse(List(FactResponse(22,22), FactResponse(45,56))))

您需要包含依赖项：

  "io.circe" %% "circe-generic" % circeVersion,
  "io.circe" %% "circe-parser"  % circeVersion,

我用过circe版本的0.10.0

你可以检查一下这里。