flutter - 如何在 ChangeNotifer 中使用 Flutter 钩子

Question

假设我们有一个带有 的复杂模型ChangeNotifer，那么当模型更改时我应该如何自动更新 UI？

这是我想出的，但看起来很奇怪，对吗，有没有更好的方法呢？

class Playground extends HookWidget {
  const Playground({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    print("built");

    final dataState = useState(DataClass(0));
    final data = useListenable(dataState.value);

    return Scaffold(
      appBar: AppBar(
        title: Text('Title'),
      ),
      body: ListView(
        children: [
          ListTile(
            title: Text("data: ${data.cnt}"),
            onTap: () {
              data.cnt++;
            },
          ),
        ],
      ),
    );
  }
}

class DataClass with ChangeNotifier {
  int _cnt;
  int get cnt => _cnt;
  set cnt(int val) {
    _cnt = val;
    notifyListeners();
  }

  DataClass(int cnt) : _cnt = cnt;
}

ps：类似useStateListenable或useListenableProvider

Answer 1

你可以结合useState起来useListenable像useListenableState

T useListenableState<T extends ChangeNotifier>(T data) {
  final state = useState<T>(data);
  return useListenable(state.value);
}

class Playground extends HookWidget {
  const Playground({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    print("built");

    final data = useListenableState(DataClass(0));

    return Scaffold(
      appBar: AppBar(
        title: Text('Title'),
      ),
      body: ListView(
        children: [
          ListTile(
            title: Text("data: ${data.cnt}"),
            onTap: () {
              data.cnt++;
            },
          ),
        ],
      ),
    );
  }
}

class DataClass with ChangeNotifier {
  int _cnt;
  int get cnt => _cnt;
  set cnt(int val) {
    _cnt = val;
    notifyListeners();
  }

  DataClass(int cnt) : _cnt = cnt;
}