Question

我正在使用RxDart观察更改并相应地更新UI。应用启动时，我正在进行网络呼叫并成功获取数据，请观察更改并相应地更新UI。但是当我在关闭屏幕的同时处理sed -E '/\.c|\.h/!d' file时。其产生以下错误：

Subjects

这是集团集团：

══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (15524): The following StateError was thrown while finalizing the widget tree:
I/flutter (15524): Bad state: You cannot close the subject while items are being added from addStream

这是我称之为的UI屏幕：

class MovieDetailBloc {
  final _repository = Repository();
  final _movieId = PublishSubject<int>();
  final _trailers = BehaviorSubject<Future<TrailerModel>>();

  Function(int) get fetchTrailersById => _movieId.sink.add;
  Observable<Future<TrailerModel>> get movieTrailers => _trailers.stream;

  MovieDetailBloc() {
    _movieId.stream.transform(_itemTransformer()).pipe(_trailers);
  }

  dispose() {
    _movieId.close();
    _trailers.close();
  }

  _itemTransformer() {
    return ScanStreamTransformer(
      (Future<TrailerModel> trailer, int id, int index) {
        print(index);
        trailer = _repository.fetchTrailers(id);
        return trailer;
      },
    );
  }
}

我关闭屏幕时出现错误。 dispose方法将引发以上异常。我该如何解决这个问题？

Answer 1

我认为排干流应该可以解决问题

  dispose() async {
    _movieId.close();
    await _trailers.drain();
    _trailers.close();
  }

https://api.dartlang.org/stable/2.0.0/dart-async/Stream-class.html

Answer 2

您还可以解决替换问题：

MovieDetailBloc() {
  _movieId.stream.transform(_itemTransformer()).pipe(_trailers);
}

使用

MovieDetailBloc() {
  _movieId.stream.transform(_itemTransformer()).listen((data) {
    if (!_categories.isClosed) {
      _trailers.add(data);
    }
  });
}

坏状态：在flutter中从addStream添加项目时，无法关闭主题

2 个答案: