StreamProvider未更新列表 [英] StreamProvider not updating List

问题描述

我有一个StreamController，它应该更新一个 List ，但不会发生:

I have a StreamController which should update a List but it doesn't happen:

class LocationService {
    StreamController<List<bg.Geofence>> geofencesController = StreamController<List<bg.Geofence>>();

    updateGeofences(geofences) {
        logger.i('listing geofences $geofences');
        geofencesController.add(List.from(list));
    }
}

当我调用 updateGeofences 时，我在日志中得到了许多地理围栏.但是小部件不会重建！

When I call updateGeofences I got many geofences in logs. But widget are not rebuilt!

这是我的提供商设置:

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MultiProvider(
        providers: [
          StreamProvider<List<bg.Geofence>>.value(
              updateShouldNotify: (_, __) {
                logger.i('updateShouldNotify, $_, $__');
                return true;
              },
              initialData: List<bg.Geofence>(),
              stream: LocationService().geofencesController.stream)
        ],
        child: MaterialApp()
     );
  }
}

当我直接从我的服务中收听时

When I listen directly from my service with

geofencesController.stream.listen((onData) {
  logger.i('Got eem! $onData');
});

流发出新数据...但不在StreamProvider中:永远不会调用 updateShouldNotify (我很幸运地尝试了 answer的解决方案)

The streams emits new data... But not in the StreamProvider: updateShouldNotify is never called (I tried without luck this answer's solutions)

这是我查看数据的方式:

Here is how I get my data in view:

class GPSView extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    List<bg.Geofence> geofences = Provider.of<List<bg.Geofence>>(context);

但是此列表仍然为空.

我还有另一个StreamController，它带有一个可以完美运行的简单Map.怎么了?

I have another StreamController with a simple Map which works perfectly. What's wrong?

推荐答案

感谢@pskink&@RémiRoussele评论我设法解决了这个问题:

So thanks to @pskink & @RémiRoussele comments I managed to fix my issue:

我正在通过调用 LocationService().geofencesController.stream 来重新创建 LocationService .

I was recreating a LocationService by calling LocationService().geofencesController.stream.

我将代码更新为

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MultiProvider(
        providers: [
          StreamProvider<List<bg.Geofence>>(
            builder: (_) => locator<LocationService>().geofencesController,
            initialData: List<bg.Geofence>(),
          ),
        ],
        child: MaterialApp();
  }
}

现在一切正常！干杯！

这篇关于StreamProvider未更新列表的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！