如何使用 Flutter Riverpod 充当 ChangeNotifierProxy Provider？

问题描述

只是想知道是否有任何方法可以以某种方式使用 Riverpod 包，它的工作方式类似于 ChangeNotifierProxy Provider。我已经制作了这个简单的代码，其中“MySecondClass”将在“MyFirstClass”更改其属性时更新。在“MySecondClass”中是一种方法，它在“MyFirstClass”更改时使用数据/变量。

到目前为止，当我按下按钮并执行 onpressed 函数时，'MySecondClass' 更新一次，但即使我再次按下按钮也保持不变。

这是提供者和类的部分：

    void main() {
  runApp(
    ProviderScope(
      child: MyApp(),),);
}

final firstClassprovider = ChangeNotifierProvider((ref) => MyFirstClass());

final secondClassprovider = ChangeNotifierProvider<MySecondClass>(
    (ref) => MySecondClass(MyFirstClass().myFirstNumber));

class MyApp extends ConsumerWidget {
  @override
  Widget build(BuildContext context,ScopedReader watch) {
    final firstClassNotifier = watch(firstClassprovider);
    final secondClassNotifier = watch(secondClassprovider);

    return MaterialApp(...


class MyFirstClass extends ChangeNotifier {
  int _myFirstNumber = 10;

  void increaseMyFirstNumber() {
    _myFirstNumber = _myFirstNumber + 1;
    notifyListeners();
  }

  get myFirstNumber => _myFirstNumber;
}

class MySecondClass extends ChangeNotifier {
  MySecondClass(this.data);
  final int data;

  int _mySecondNumber = 2;

  void receiveNumberFromClass1() {
    _mySecondNumber = data;
    print('$data Data');
    notifyListeners();
  }

  get mySecondNumber => _mySecondNumber;
}

如果你想复制这个例子的全部代码，这里是：

   import 'package:Flutter/material.dart';
import 'package:Flutter_riverpod/all.dart';
import 'package:riverpod/riverpod.dart';
import 'package:riverpod/all.dart';

void main() {
  runApp(
    ProviderScope(
      child: MyApp(),ScopedReader watch) {
    final firstClassNotifier = watch(firstClassprovider);
    final secondClassNotifier = watch(secondClassprovider);

    return MaterialApp(
      home: Scaffold(
        body: Container(
          color: Colors.blueGrey,alignment: Alignment.center,child: Column(
            mainAxisAlignment: MainAxisAlignment.center,crossAxisAlignment: CrossAxisAlignment.center,children: [
              Text(
                firstClassNotifier._myFirstNumber.toString(),style: TextStyle(fontSize: 40),Text(secondClassNotifier.mySecondNumber.toString()),MaterialButton(
                  child: Container(
                    height: 50,width: 50,color: Colors.deepOrangeAccent,onpressed: () {
                    firstClassNotifier.increaseMyFirstNumber();
                    secondClassNotifier.receiveNumberFromClass1();
                  }),],);
  }
}

class MyFirstClass extends ChangeNotifier {
  int _myFirstNumber = 10;

  void increaseMyFirstNumber() {
    _myFirstNumber = _myFirstNumber + 1;
    notifyListeners();
  }

  get myFirstNumber => _myFirstNumber;
}

class MySecondClass extends ChangeNotifier {
  MySecondClass(this.data);
  final int data;

  int _mySecondNumber = 2;

  void receiveNumberFromClass1() {
    _mySecondNumber = data;
    print('$data Data');
    notifyListeners();
  }

  get mySecondNumber => _mySecondNumber;
}

解决方法

在做了一些研究和测试之后，我找到了一种方法。不确定这是否是你应该做的方式。但到目前为止它工作正常。这就是我添加的代码：

final firstClassProvider = ChangeNotifierProvider((ref) => MyFirstClass());

final secondClassProvider = ChangeNotifierProvider<MySecondClass>((ref) {
  final secondClass = MySecondClass(MyFirstClass().myFirstNumber);
  return secondClass;
});


class MySecondClass extends ChangeNotifier {
  MySecondClass(this.data);
  final int data;

  int _mySecondNumber = 2;
  int _myOtherNumber = 8;

  void updateClass2(number) {
    _myOtherNumber = number;
    print('$_myOtherNumber other Number');
  }

  void receiveNumberFromClass1() {
    _mySecondNumber = _myOtherNumber;
    print('$data Data');
    notifyListeners();
  }

  get mySecondNumber => _mySecondNumber;
}