Question

我正在尝试在Akka / Scala中编写一个调用HTTP REST API并将结果发送回调用actor的actor。 API可能会返回结果的集合/向量，这些结果必须首先转换为内部供应商中性格式，以便将来可以更改供应商，而无需对代码进行太多更改。大多数代码都在工作，但我不确定如何解压缩并发送内部向量。

这是我的代码，它向调用的actor返回Promise。我想要返回的是在最终map操作中创建的实际向量：

class RESTActor extends Actor with ActorLogging with JsonSupport {

  final implicit val materializer: ActorMaterializer = ActorMaterializer(ActorMaterializerSettings(context.system))
  val http = Http(context.system)

  import akka.pattern.pipe
  import context.dispatcher

  override def receive: Receive = {
    case query: String => {
      val requester = sender
      var uri = Uri(Settings.autoCompleteURL).withQuery(Query(Map("query" -> query)))

      sender! http
        .singleRequest(HttpRequest(HttpMethods.GET, uri = uri))
        .flatMap(response =>
          response.status match {
            case status if status.isSuccess() => Unmarshal(response.entity).to[VendorResponse].map(_.result.map(x => VendorNeutralResponse(x.id, x.field)))

            case _ => response.entity.toStrict(5.seconds).map { entity =>
              val body = entity.data.decodeString("UTF-8")
              log.warning(errorMessage(response, body))
              Left(errorMessage(response, body))
            }

          })
    }

  }

主演：

pathPrefix("search") {
          get {
            parameter("query") { query =>
              {
                complete(restActor.ask(query)) //Doesn't work as the reply is a promise

              }
            }
          }
        }

如何更改RESTActor中的上述代码以发回实际结果而不是未来或承诺？

修改：根据我自己的研究和@michał和@ cyrille-corpet的建议更改代码后，以下代码有效：

pathPrefix("search") {
          get {
            parameter("query") { query =>
              {
                onComplete(gisRouter.ask(query)) {
                  case Success(resp: Future[Vector[VendorNeutralResponse]]) => {
                    resp.map(println)
                    complete("ok")
                  }
                  case Failure(e) => complete(e.toString)
                }

              }
            }
          }
        }

似乎我仍然得到future来自我的演员的回应。如何让演员回复实际数据而不是Future？

Answer 1

您可以使用onComplete函数作为输入Future[T]，并返回Directive1[Try[T]]，以便您可以使用以下内容：

pathPrefix("search") {
  get {
    parameter("query") { query =>
      onComplete(restActor.ask(query)) {
        case Success(resp) => ...
        case Failure(e) => ...
      }
    }
  }
}

编辑关于演员的回复，你应该将http.singleRequest的结果传递给发件人，而不是告诉它：

http.singleRequest(...).flatMap(...) pipeTo requester

这样，实际的tell（!）只有在Future被解析后才会完成。

Answer 2

你可以使用map来实现monadic：

pathPrefix("search") {
  get {
    parameter("query") { query =>
      restActor.ask(query) map {
        case Success(resp) => ...
        case Failure(e) => ...
      }
    }
  }
}

编辑：目前您的演员回应未来。尝试重构它，以便它确实返回unwrapped值：

class RESTActor extends Actor with ActorLogging with JsonSupport {

  final implicit val materializer: ActorMaterializer = ActorMaterializer(ActorMaterializerSettings(context.system))
  val http = Http(context.system)

  import akka.pattern.pipe
  import context.dispatcher

  private def handleHttpResponse = {
    case status if status.isSuccess() => Unmarshal(response.entity).to[VendorResponse].map(_.result.map(x => VendorNeutralResponse(x.id, x.field)))

    case _ => response.entity.toStrict(5.seconds).map { entity =>
      val body = entity.data.decodeString("UTF-8")
      log.warning(errorMessage(response, body))
      Left(errorMessage(response, body))
    }

  }

  override def receive: Receive = {
    case query: String => {
      val requester = sender
      var uri = Uri(Settings.autoCompleteURL).withQuery(Query(Map("query" -> query)))

      http.singleRequest(HttpRequest(HttpMethods.GET, uri = uri)).flatMap(response =>
          response.status map handleHttpResponse ) pipeTo requester
    }

  }

从Actor而不是Promise / Future返回实际结果

2 个答案: