Flutter Bloc 使用 transformEvents 按事件值对事件队列进行排序

Question

有没有一种简单的方法可以根据事件的值 class 对 flutter bloc 的事件队列进行排序？例如。我有一个带有 int 属性的 class MyEvent，事件队列如下所示：

[MyEvent(5), MyEvent(3), MyEvent(7), AnotherEvent(), MyEvent(2), MyEvent(1)]

我想对事件queue/stream进行改造，让int值最小的事件属性先执行-> [MyEvent(3), MyEvent(5), MyEvent(7), AnotherEvent(), MyEvent(1), MyEvent(2)]

应该可以通过覆盖 transformEvents somehow and maybe using an extension of rxdart 来实现，但我无法做到正确，如果有人能帮助我，我会很高兴。提前致谢！

Answer 1

感谢@narcodico, he posted this answer to my question on the flutter bloc github https://github.com/felangel/bloc/issues/2441

  @override
  Stream<Transition<SortEvent, SortState>> transformEvents(
    Stream<SortEvent> events,
    transitionFn,
  ) {
    return events
        .bufferTest((event) => event is BreakEvent)
        .flatMap<SortEvent>((bufferedEvents) async* {
      final sortedEvents = bufferedEvents.whereType<ValueEvent>().toList()
        ..sort((x, y) => x.value.compareTo(y.value));
      yield* Stream<SortEvent>.fromIterable([
        ...sortedEvents,
        ...bufferedEvents.whereType<BreakEvent>(),
      ]);
    }).asyncExpand(transitionFn);
  }

Flutter Bloc 使用 transformEvents 按事件值对事件队列进行排序

Flutter Bloc Sorting event queue by a value of the event with transformEvents

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