akka-http：找不到参数解组的隐式值

Question

我的喷雾 json 支持看起来像这样

object MarshallingSupport extends SprayJsonSupport {
  implicit def json4sFormats: Formats = DefaultFormats
}

在我的路线中，我想将请求映射到 dto

object Main extends App with AppConfig with BaseService with MainActorSystem {

  val processor = system.actorOf(Props(), "processorActor")
  val view = system.actorOf(Props(), "processorActor")

  override protected implicit val executor: ExecutionContext = system.dispatcher
  override protected val log: LoggingAdapter = Logging(system, getClass)
  override protected implicit val materializer: ActorMaterializer = ActorMaterializer()

  Http().bindAndHandle(routes(processor, view), httpInterface, httpPort)
}

trait BaseServiceRoute {
  protected implicit def executor: ExecutionContext
  protected implicit def materializer: ActorMaterializer
  protected def log: LoggingAdapter
}

trait MainActorSystem {
  implicit val system = ActorSystem("booking")
}

final case class CalculatePriceForRangeDto(unitId: Int, from: Long, to: Long)

trait PriceServiceRoute extends BaseServiceRoute {

  implicit val timeout = Timeout(30 seconds)

  import com.example.crudapi.utils.MarshallingSupport._

  def customersRoute(command: ActorRef, query: ActorRef) = pathPrefix("price") {
    post {
      path("calculate") {
        decodeRequest {
          entity(as[CalculatePriceForRangeDto]) {
            priceForRange => onComplete((query ? CalculatePriceForRange(

但我得到

Error:(32, 20) could not find implicit value for parameter um: akka.http.scaladsl.unmarshalling.FromRequestUnmarshaller[com.example.crudapi.http.routes.CalculatePriceForRangeDto]
      entity(as[CalculatePriceForRangeDto]) {
               ^

看过所有相关的 SO 问题，但没有解决我的问题。奇怪的是，我尝试了 Typesafe 模板 akka-dddd-cqrs 并且它可以工作，代码相同。

我是否缺少带有隐式上下文的东西？任何想法可能是什么？

Answer 1

SprayJsonSupport适用于 Spray-json（不适用于 json4s）。因此，您需要按如下方式定义编组器

trait JsonMarshallers extends DefaultJsonProtocol {
  implicit val DigestItemWireFormat = jsonFormat6(DigestItemWire.apply)

  implicit val LocalDateTimeFormat = new JsonFormat[LocalDateTime] {

    private val iso_date_time = DateTimeFormatter.ISO_DATE_TIME

    def write(x: LocalDateTime) = JsString(iso_date_time.format(x))

    def read(value: JsValue) = value match {
      case JsString(x) => LocalDateTime.parse(x, iso_date_time)
      case x => throw new RuntimeException(s"Unexpected type %s on parsing of LocalDateTime type".format(x.getClass.getName))
    }
  }
}

然后JsonMarshallers._在您使用它们的范围内导入或将其与文件开头混合PriceServiceRoute并导入akka.http.scaladsl.marshallers.sprayjson.SprayJsonSupport._。