处理失败的期货 [英] Dealing with failed futures

问题描述

在Play Framework 2.3中，操作可以从成功的将来调用中产生结果，如下所示:

In Play Framework 2.3, an action can produce a result from a successful future call like this:

def index = Action.async {
  val futureInt = scala.concurrent.Future { intensiveComputation() }
  futureInt.map(i => Ok("Got result: " + i))
}

但是，动作如何处理失败的将来调用，即通过调用failure()而不是success()完成的将来?

But how can an action deal with a failed future call, i.e., a future that was completed by calling failure() instead of success()?

例如，一个动作如何产生InternalServerError结果，并在将来的故障的throwable中返回消息?

For instance, how could an action produce a InternalServerError result with the message returned in the future's failure's throwable?

onComplete和onFailure回调似乎与操作流程不符(它需要从成功的未来或失败的未来返回结果).

onComplete and onFailure callbacks don't seem to fit the action's flow (it needs to return a result, either from a successful future or a failed one).

推荐答案

对于单个Action，您可以使用recover执行此操作，将失败的Future恢复到Result:

For a single Action, you can do this with recover, recovering the failed Future to a Result:

def index = Action.async {
    val futureInt = scala.concurrent.Future { intensiveComputation() }
    futureInt.map(i => Ok("Got result: " + i))
        .recover{ case e: Exception => InternalServerError(e.getMessage) }
}

在这种情况下，

recover是PartialFunction[Throwable, Result]，因此您可以更加精细地进行错误处理，并且PartialFunction中未定义的任何内容都将是失败的Future.更一般而言，您可能会使用实现此目的的自定义定义的Action.

recover in this case is a PartialFunction[Throwable, Result], so you can be more fine grained with your error handling, and anything that is not defined in the PartialFunction will remain a failed Future. More generally, you could probably use a custom defined Action that implements this.

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