Circe DeliverDecoder/deriveEncoder 无法找到 io.circe.generic.encoding.DerivedAsObjectEncoder 类型的 Lazy 隐式值

Question

我正在尝试为两个案例类生成编码器和解码器：

object EventBusCases {
  case class ValuationRequest(function: RequestValue = ALL_DAY_VALS, interval: RequestValue = IntraDayIntervals.MIN_5)
  implicit val requestDecoder: Decoder[ValuationRequest] = deriveDecoder[ValuationRequest]
  implicit val requestEncoder: Encoder[ValuationRequest] = deriveEncoder[ValuationRequest]

  case class ValuationResponse(values: List[Valuation], function: RequestValue)
  implicit val responseDecoder: Decoder[ValuationResponse] = deriveDecoder[ValuationResponse]
  implicit val responseEncoder: Encoder[ValuationResponse] = deriveEncoder[ValuationResponse]
}

我不断收到这样的错误，但对于这两种情况： could not find Lazy implicit value of type io.circe.generic.encoding.DerivedAsObjectEncoder[eventbus.eventBusCases.ValuationResponse]

我决定还尝试为这些类中的自定义类派生编码器和解码器，例如“Valuation”，但我在这些类上遇到了相同的错误。

我正在使用Circe 0.12.3这些Scala 2.12.8是我的 Circe 相关的 Scala 依赖项：

  "com.beachape" %% "enumeratum" % "1.5.14",
  "com.beachape" %% "enumeratum-circe" % "1.5.22",
  "io.circe" %% "circe-core" % "0.12.3",
  "io.circe" %% "circe-generic" % "0.12.3",
  "io.circe" %% "circe-parser" % "0.12.3"

Answer 1

因此，我发现实现这项工作的方法是为 ValuationRequest 和 ValuationResponse 以及其中包含的所有自定义类型实现编码器和解码器。

对于 ValuationRequest 和 ValuationResponse，我基本上将此位添加到包含两个案例类的同一文件中：

object derivation {
  implicit val encodeResponse: Encoder[ValuationResponse] = Encoder.instance {
    case response @ ValuationResponse(_,_) => response.asJson
  }
  implicit val decodeResponse: Decoder[ValuationResponse] =
    List[Decoder[ValuationResponse]](
      Decoder[ValuationResponse].widen
    ).reduceLeft(_ or _)

  implicit val encodeRequest: Encoder[ValuationRequest] = Encoder.instance {
    case response @ ValuationRequest(_,_) => response.asJson
  }
  implicit val decodeRequest: Decoder[ValuationRequest] =
    List[Decoder[ValuationRequest]](
      Decoder[ValuationRequest].widen
    ).reduceLeft(_ or _)
}