带有 akka-http 的 Scala 未来

Question

我需要用 akka-http 和 reactivemongo 编写简单的网络服务。

保存数据的函数如下所示

 def saveRoute(route: Route):Future[WriteResult] = {
    collection.insert(route)
 }

调用此函数的代码如下所示

val userRoutes = {
    logRequestResult("akka-http-microservice") {
      path("routes") {
        (post & entity(as[Route])) { route =>
          Database.saveRoute(route)
        }
      }
    }
  }

我需要 return 使用插入的路由 ID 生成结果，并且在不让线程等待的情况下执行此操作。如果尝试

Database.saveRoute(route).onComplete{
            case Success(r) => complete(r.toString)
            case Failure(e) => complete(e.getMessage)
          }

它无法编译，因为它没有 return 值。我知道如何以肮脏的方式制作它，但真的想以适当的方式制作。

这种情况应该怎么办？

Answer 1

这个怎么样，替换：

Database.saveRoute(route)

与：

complete(Database.saveRoute(route).map(_.toString).recover(_.getMessage))

Answer 2

您可以映射未来，然后完成如下请求。

val future = Database.saveRoute(route)
val response = future.map(_.getId).recover(_.getMessage)
complete(response)

附带说明一下，为了处理异常，最好有一个 ExceptionHandler 并将其包装在您的路由中。您可以找到示例 here.

Answer 3

使用 onSuccess 处理未来完成时的有效响应，使用 handleExceptions 处理未来不成功的响应。

   val userRoutes = {
    handleExceptions(mongoDbExceptionHandler) {
      logRequestResult("akka-http-microservice") {
        path("routes") {
          (post & entity(as[Route])) { route =>
            onSuccess(Database.saveRoute(route)) { result =>
              complete(result)
            }
          }
        }
      }
    }
  }

  // Something like this for whatever the exceptions you expect are
  val mongoDbExceptionHandler = ExceptionHandler {
    case ex: MongoDbReadException => complete(HttpResponse(InternalServerError, "No database")))
  }

成功时： http://doc.akka.io/docs/akka/2.4.9/scala/http/routing-dsl/directives/future-directives/onSuccess.html

处理异常： http://doc.akka.io/docs/akka/2.4.9/scala/http/routing-dsl/exception-handling.html

Answer 4

看来我找到了最有效的方法。它内置于 onComplete 指令

(path("routes" / "add") & post & entity(as[Route])) {
    route =>
      onComplete(routesController.addRoute(route)) {
        case Success(result) => complete(StatusCodes.Created, "OK")
        case Failure(ex) => complete(new ErrorResponse(StatusCodes.InternalServerError.intValue, ErrorResponse.ERROR, ex.getMessage))
      }
  }

Answer 5

你没有多少选择，我会尝试将最常用的选项用于基于 REST API 的解决方案：

OnSuccess 当你希望你的期望冒泡并由 expectionHandler 处理时使用它

  concat(
    path("success") {
      onSuccess(Future { "Ok" }) { extraction =>
        complete(extraction)
      }
    },
    path("failure") {
      onSuccess(Future.failed[String](TestException)) { extraction =>
        complete(extraction)
      }
    }
  )

https://doc.akka.io/docs/akka-http/current/routing-dsl/directives/future-directives/onSuccess.html

onComplete：当你想手动处理异常时。尝试包裹 Monad。

val route =
  path("divide" / IntNumber / IntNumber) { (a, b) =>
    onComplete(divide(a, b)) {
      case Success(value) => complete(s"The result was $value")
      case Failure(ex)    => complete((InternalServerError, s"An error occurred: ${ex.getMessage}"))
    }
  }

https://doc.akka.io/docs/akka-http/current/routing-dsl/directives/future-directives/onComplete.html

带有 akka-http 的 Scala 未来

Scala future with akka-http

scala

akka-http