当嵌套对象内的属性更改时，提供程序不会更新

Question

我有一个初始化多个对象的模型。每当其中一个对象内的属性发生更改时，用户界面就不会重建。我负责使用 Equatable 覆盖对象的哈希和 ==，以便提供程序应该检测到更改。以下是显示重要部分的代码示例：

class Tag extends ChangeNotifier with EquatableMixin {
  Tag(this._title, this._value, this._selected);

  final String _title;
  String _value;
  bool _selected;

  @override
  List<Object> get props => [_title, _value, _selected];

  String get title => _title;

  String get value => _value;
  set value(String newValue) {
    _value = newValue;
    notifyListeners();
  }

  bool get selected => _selected;
  set selected(bool newValue) {
    _selected = newValue;
    notifyListeners();
  }
}

class TagModel extends ChangeNotifier {
  TagModel() {
    _tag1.addListener(notifyListeners);
    _tag2.addListener(notifyListeners);
    _tag3.addListener(notifyListeners);
  }

  final Tag _tag1 = Tag("", "", false);
  final Tag _tag2 = Tag("", "", false);
  final Tag _tag3 = Tag("", "", false);

  Tag get tag1 => _tag1;
  Tag get tag2 => _tag2;
  Tag get tag3 => _tag3;
  

  //this function does not trigger a widget rebuild
  void loadTags() {
    _tag1.title = "tag 1";
    _tag2.title = "tag 2";
    _tag3.title = "tag 3";
  }
}

class TagPane extends StatelessWidget {
  const TagPane({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    //this does not change when loadTags function is called 
    final tag1 = context.select((TagModel tagModel) => tagModel.tag1)
    return Container(
      .
      .
      .
      ElevatedButton(
        onPressed: () => context.read<TagModel>().loadTags(),
      )
    );
  }
}

Answer 1

您是否尝试在方法末尾添加对 NotifyListeners() 的调用？

Answer 2

当按下提升按钮时，尝试使用 Statefull Widget 而不是 Stateless 而非 setState。例如

class TagPane extends StatefullWidget {
  const TagPane({Key? key}) : super(key: key);
  
  @override
  _TagPaneState createState() => _TagPaneState();
}

class _TagPaneState extends State<TagPane>{
  @override
  Widget build(BuildContext context) {
    //this does not change when loadTags function is called 
    final tag1 = context.select((TagModel tagModel) => tagModel.tag1)
    return Container(
      .
      .
      .
      ElevatedButton(
        onPressed: () => setState(() { 
          context.read<TagModel>().loadTags());
        ),
      )
    );
  }
}