RxJava2 |如何处理一组 Maybes

Question

我正在重构代码以使用 RoomDataBase 和 RxJava2。我有一个数据源，它通过 id 和 returns 获取一行，也许

 override fun getByAppWidgetId(appWidgetId: Int): Maybe<LocationWidget> {
    return mDB.locationDao().getByAppWidgetId(appWidgetId)
}

在其他地方，我得到一个 appWidgetId 数组，我想为其获取每个 ID 的行条目。我想将所有的 Maybe 组合成一个 Observable 和

private fun hasCurrentLocationWidget(appWidgetIds: IntArray): Single<Boolean> {
  observableOfMaybes: Observable // something to hold the maybes we're about to get

  for (appWidgetId in appWidgetIds) {
    locationMaybe: Maybe<LocationWidget> = dataSource.getByAppWidgetId(appWidgetId)
    // -> add each Maybe to `observableOfMaybes`
  }

  return observableOfMaybes
    .subscribeOn(Schedulers.newThread())
    // somehow return if any of the `isCurrentLocation` are true
    .filter({ location -> location.isCurrentLocation == true })
    .toSingle()
}

Answer 1

您可以使用 flatMapMaybe() 创建 Maybes 的 Observable。为此，您需要将 IntArray 转换为 vararg。

Observable.fromArray(*appWidgetIds.toTypedArray())
        .flatMapMaybe { getByAppWidgetId(it) }

RxJava2 |如何处理一组 Maybes

RxJava2 | How to process a group Maybes

android

kotlin

rx-java2

android-room