从多个 HTTP 请求中提取和累积结果

Question

这几天遇到了一个无法解决的问题。我正在执行多个 http 请求，在每个响应中，它应该有一个 Array[DTAnnotation]。我想将所有结果列表累积成一个（这不是这里的问题）。我的问题是我无法 return 来自 WSResponse 的结果。我的尝试：

import mymodel.{DTFeatures, DTResponse, DTRequest, DTAnnotations}

def checkForSpike
  (
    awsKey : String,
    collection : JSONCollection,
    record : Record,
    features : Array[DTFeatures]
  ) : Unit = {
  val url = config.getString("url").getOrElse 
  val holder = WS.url(url)
  val complexHolder =
    holder.withHeaders(("Content-Type","application/json"))
  // excepting result is List[Array[DTAnnotations]] 
  val test : List[Array[DTAnnotations]] = 
  for(feature <- features) yield {
    val dtFeature = Json.stringify(Json.toJson(DTRequest(feature)))
    val futureResponse = complexHolder.post(dtFeature)
    Logger.info("Make the HTTP POST Request in " + (t1 - t0) + " msecs")
    futureResponse.map { response =>
      Logger.info("Get response in " + (System.currentTimeMillis - t1))
      if(response.status == 200) {
        response.json.validate[DTResponse].map { dtResponse =>
          // I want to return this 
          dtResponse.annotations 
        }.recoverTotal { _ =>
          Logger.debug("invalid json")
        }
      } else {
        Logger.debug(Json.prettyPrint(Json.obj("status" -> response.status, "body" -> response.body)))
      }
    }
        Await.result(futureResponse, 10.seconds)
  }
}

因为响应是 Future，我尝试添加一个 Await 来获取注释，但我在输入阶段有一个错误：

[error]  found   : Array[play.api.libs.ws.WSResponse]
[error]  required: List[Array[DTAnnotation]]

我该如何解决这个问题？谢谢！

Answer 1

有许多错误可以避免此操作。我添加了一个与您期望的类型编译的版本，如果您有任何问题，我会在评论中回答。

def checkForSpike
  (
    awsKey: String,
    collection: JSONCollection,
    record: Record,
    features: Array[DTFeatures]
  ): Unit = {
    val url = config.getString("url").getOrElse
    val holder = WS.url(url)
    val complexHolder =
      holder.withHeaders(("Content-Type", "application/json"))
    // excepting result is List[Array[DTAnnotations]]
    val test: List[Array[DTAnnotations]] =
      for (feature <- features.toList) yield {
        val dtFeature = Json.stringify(Json.toJson(DTRequest(feature)))
        val futureResponse = complexHolder.post(dtFeature)
        val futureAnnotations: Future[Array[DTAnnotations]] = futureResponse.map { response =>
          if (response.status == 200) {
            response.json.validate[DTResponse].map { dtResponse =>
              // I want to return this
              dtResponse.annotations
            }.recoverTotal { _ =>
              Logger.debug("invalid json")
              ??? // An Array response should be expected, maybe empty
            }
          } else {
            Logger.debug(Json.prettyPrint(Json.obj("status" -> response.status, "body" -> response.body)))
            ??? // An Array response should be expected, maybe empty
          }
        }

        Await.result(futureAnnotations, 10.seconds)
      }
  }

问题：

如果您希望列表成为要素，则必须将要素转换为列表由 for comprehension
未来响应地图returns 另一个未来，这个值应该用在 Await
为了确保 futureAnnotations 的类型在所有分支中都是正确的，类型应该是有效的

从多个 HTTP 请求中提取和累积结果

Extracting and accumulate result from multiple HTTP request

scala

playframework

playframework-2.0

future