Scala，Spray - 解组到列表 [Int]

Question

我正在尝试从 JSON api 获取整数列表 [1,2,3,...]，但我发现转换为通用类型无效，Spray 文档仅显示解组到特定目的。任何想法如何让它工作/如何 google 得到我的答案？

API 端点：https://hacker-news.firebaseio.com/v0/newstories.json

import java.io.IOException

import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.unmarshalling.Unmarshal
import akka.stream.ActorMaterializer
import akka.stream.scaladsl.{Flow, Sink, Source}
import akka.http.scaladsl.model.{HttpResponse, HttpRequest}
import com.typesafe.config.ConfigFactory
import akka.http.scaladsl.model.StatusCodes._
import spray.json.DefaultJsonProtocol._
import spray.json._
import akka.http.scaladsl.client.RequestBuilding
import scala.concurrent.Future

object NewsDaemon extends App{
  val config = ConfigFactory.load()

  implicit val system = ActorSystem()
  implicit val executor = system.dispatcher
  implicit val materializer = ActorMaterializer()

  case class HNResultList(items: List[Int])

  val hnConnectionFlow: Flow[HttpRequest, HttpResponse, Any] =
    Http().outgoingConnectionTls(config.getString("services.hnApiHost"))

  def hnApiRequest (request: HttpRequest) : Future[HttpResponse] = Source.single(request).via(hnConnectionFlow).runWith(Sink.head)

    hnApiRequest(RequestBuilding.Get("/v0/topstories.json?print=pretty")).flatMap { response =>
      response.status match {
        case OK => Unmarshal(response.entity).to[List[Int]].map(println)
        case _ => Unmarshal(response.entity).to[String].flatMap { entity =>
          val error = s"HN API request failed with status code ${response.status} and entity $entity"
          Future.failed(new IOException(error))
        }
      }
    }
}

Answer 1

试试 akka.http.scaladsl.marshallers.sprayjson.SprayJsonSupport:

object NewsDaemon extends App with SprayJsonSupport {
...
}

spray-json 库支持基本类型和 collections 'out-of-box'.

您可以在此处找到实现：

基本类型：spray.json.BasicFormats
collections: spray.json.CollectionFormats

因此您不必为此类型编写自己的 JsonFormat (JsonReader/JsonWriter)。

有关如何将 spray-json 与 akka-http 集成的详细说明，您可以在此处找到：http://doc.akka.io/docs/akka-stream-and-http-experimental/2.0.3/scala/http/common/json-support.html

Scala，Spray - 解组到列表 [Int]

Scala, Spray - Unmarshalling to List[Int]

json

scala

spray

spray-json

akka-http