Question

有没有方法可以忽略以下没有failed的地图/平面图？

这就是我所拥有的：

  def delete(serverId: UUID) = authAction.async { implicit request =>
    val user = request.user.get
    serverService.findByIdAndUserId(serverId, user.id.get)
      .flatMap{s =>
        if (s.isEmpty) {
          Future.failed(new DeleteFailedException)
          // Can I return a `NotFound("...")` here instead of failed?
        } else {
          Future.successful(s.get)
        }
      }
      .map{s =>
        serverService.delete(s)
      }.map{_ =>
      Ok(Json.toJson(Map("success" -> "true")))
    }
  }

当我在NotFound("...")中返回flatMap时，以下map仍然会被执行。有没有办法忽略以下地图/平面图？

Answer 1

而不是使用异常执行Future.failed。你可以返回一个。关于它们的好处是你可以在它上进行模式匹配，然后构造适当的http响应。

def delete(serverId: UUID) = authAction.async { implicit request =>
  val user = request.user.get
  serverService.findByIdAndUserId(serverId, user.id.get)
    .flatMap{s =>
      if (s.isEmpty) {
        Left(new DeleteFailedException)
      } else {
        Right(s.get)
     }
   }
   .map{s => s match {
     case Left(notFound) => 
        // construct the Json for failure
     case Right(s) => 
        serverService.delete(s)
        // construct json for success.
   }}
 }

Answer 2

认为应该没问题（我假设findByIdAndUserId返回Future [Option [_]]，而不是Option[_]，如您在评论中所回答的那样）。在我的方法中，我还删除了get和不必要的map

的使用情况

def delete(serverId: UUID) = authAction.async { implicit request =>
  val user = request.user.get

  request.user.flatMap(_.id).fold {
    Future.successfull(NotFound("no user"))
  } {userId =>
    serverService.findByIdAndUserId(serverId, userId).map {
      case None =>
        NotFound("no server")
      case Some(s) =>
        serverService.delete(s)
        Ok(Json.toJson(Map("success" -> "true")))
    }
  }
}

Play框架会忽略以下地图/ flatmap

2 个答案: