基本的akka​​ http客户端帖子不能正常工作

Question

我正在尝试让一个基本的http客户端使用Akka HTTP将一些数据发布到REST API，但是我无法使以下代码工作：

def sendData(e : GenericEvent): Future[Either[(String,StatusCode),(GenericEvent,StatusCode)]] = {

val request = Marshal(e).to[RequestEntity]
val responseFuture: Future[HttpResponse] = request map { req =>
  Source.single(HttpRequest(method = HttpMethods.POST, uri = s"/data-ingest", headers = List(auth), entity = req))
    .via(dataIngestFlow)
    .runWith(Sink.head)
}

responseFuture.flatMap { response =>
  response.status match {
    case OK => Unmarshal(response.entity).to[GenericEvent].map(Right(_, response.status))
    case BadRequest => Future.successful(Left(s"$e.data: incorrect data", response.status))
    case _ => Unmarshal(response.entity).to[String].flatMap { entity =>
      val error = s"generic event ingest failed with status code ${response.status} and entity $entity"
      logger.error(error)
      Future.failed(new IOException(error))
    }
  }
}

我收到以下错误

polymorphic expression cannot be instantiated to expected type;
[error]  found   :      
[T]akka.stream.scaladsl.Sink[T,scala.concurrent.Future[T]]
[error]  required:         
akka.stream.Graph[akka.stream.SinkShape[akka.http.scaladsl.model.HttpResponse],akka.http.scaladsl.model.HttpResponse]
[error]         .runWith(Sink.head)

以下是dataIngestFlow的代码

val dataIngestFlow = Http().outgoingConnection(config.endpointUrl,config.endpointPort)

以下是服务器端的代码：

val routes = {
    logRequestResult("akka-http-microservice") {
      path("event-ingest") {
        post {
          entity(as[GenericEvent]) { eventIngest =>
            log.info(s"Ingesting {} and publishing event to Kafka topic {}.", eventIngest.eventType,config.kafkaTopic)
            kafka ! eventIngest
            complete {
              eventIngest
            }
          }~
            entity(as[List[GenericEvent]]) { eventIngestList =>
              eventIngestList.foreach{ eventIngest=>
                log.info(s"Ingesting {} and publishing event List to Kafka topic {}.", eventIngest.eventType,config.kafkaTopic)
                kafka ! eventIngest
              }
              complete {
                eventIngestList
              }
            }
        }
      }
    }
  }

我尝试了另一个简单的客户端，它构建得很好但是在160个事件之后摄取停止，服务器不再接收任何事件。

Answer 1

我在您的示例中看到的第一个问题是RequestEntity没有地图功能。因此，以下一行

val responseFuture: Future[HttpResponse] = request map { ...

不应该编译。

此外，如果request实际上是一个Future（我在地图中推断），那么responseFuture实际上是Future[Future[HttpResponse]]类型，因为该流实现了它自己的Future。要解决此问题，您可以使用Future.flatMap代替地图。即：

val responseFuture: Future[HttpResponse] = request flatMap { req =>

这是Futures中的monadic bind operation。