映射失败的未来的例外 [英] Map the Exception of a failed Future

问题描述

映射失败的未来异常的最干净的方法是什么？ c $ c>在scala中？

What's the cleanest way to map the Exception of a failed Future in scala?

说我有：

import scala.concurrent._
import scala.concurrent.ExecutionContext.Implicits.global

val f = Future { 
  if(math.random < 0.5) 1 else throw new Exception("Oh no") 
}

如果Future成功且 1 ，我想保留，但是如果失败，我想将 Exception 更改为另一个 Exception 。

If the Future succeeds with 1, I'd like to keep that, however if it fails I would like to change the Exception to a different Exception.

我能想到的最好的方法是变换，但是这需要我为成功案例做一个不必要的功能：

The best I could come up with is transform, however that requires me to make a needless function for the success case:

val f2 = f.transform(s => s, cause => new Exception("Something went wrong", cause))

是否有任何原因没有 mapFailure（PartialFunction [Throwable ，Throwable]）？

推荐答案

还有：

f recover { case cause => throw new Exception("Something went wrong", cause) }

从Scala 2.12开始，您可以执行以下操作：

Since Scala 2.12 you can do:

f transform {
  case s @ Success(_) => s
  case Failure(cause) => Failure(new Exception("Something went wrong", cause))
}

或

f transform { _.transform(Success(_), cause => Failure(new Exception("Something went wrong", cause)))}

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