Combining/chaining scala play 框架异步操作中的期货

Question

我是一个 scala 新手，正在尝试使用 play 框架编写 Rest Api。我有以下3种数据访问方式

getDataDict: (dsType:String, name:String) => Future[Option[DatasetDictionary]]
getDatasetData: (DatasetDictionary) => Future[List[DatasetData]]
getMetadata: (DatasetDictionary) => Future[List[Metadata]]

我需要使用这 3 种方法来获取异步操作方法的结果。

 def index(dstype:String, name:String, metadata:Option[Boolean]) = Action.async{   
  /*
     1. val result = getDataDict(type, name)
     2. If result is Some(d) call getDatasetData
     3.1 if metadata = Some(true)
          call getMetadata function
          return Ok((dict, result, metadata))
     3.2 if metadata is None or Some(false)
          return Ok(result)
     4. If result is None
               return BadRequest("Dataset not found")
 */  
}

我的步骤 1 和 2 工作如下

def index1(dsType:String, dsName: String, metadata:Option[Boolean]) = Action.async {
    getDataDict(dsType, dsName) flatMap {
        case Some(x) => getDatasetData(x) map (x => Ok(Json.toJson(x)))
        case None => Future.successful(BadRequest("Dataset not found"))
      }
}

我对如何让元数据部分起作用感到困惑。

Answer 1

首先，不是很清楚(d,result,x)你到底想要什么return。希望我猜对了：

 def index(dstype:String, name:String, metadata:Option[Boolean]) = Action.async {
    getDataDict(dstype, name) flatMap {
      case Some(datasetDictionary) =>
        getDatasetData(datasetDictionary) flatMap { datasetDataList =>
          if (metadata == Some(true)) {
            getMetadata(datasetDictionary) map { metadataList =>
              Ok(Json.toJson((datasetDictionary, datasetDataList, metadataList)))
            }
          } else {
            Future.successful(Ok(Json.toJson(datasetDataList)))
          }
        }
      case None => Future.successful(BadRequest("Dataset not found"))
    }
  }

Combining/chaining scala play 框架异步操作中的期货

Combining/chaining futures in scala play framework async action

scala

future

playframework

playframework-2.0