我试图使用observe包,而不必在模型中具有批注,而仅通过在 setter 中提高notifyPropertyChange,因此要进行测试,我进行了以下测试

import 'package:observe/observe.dart';
import 'dart:async';
import 'dart:math';
void main() {

  var dummyWatchingModel = new DummyWatchingModel();
  new Timer.periodic(new Duration(milliseconds:1000), (_){
           //calls a function that set a random value to the property in the observable model
           dummyWatchingModel.setModelProps();
      });
}

class Model extends Observable{
  int _x;
  Model(this._x);

  int get x=> _x;
  void set x(int value){
    _x = notifyPropertyChange(#_x, _x, value);
  }
}

class DummyWatchingModel{
  Model model = new Model(1);
  final rng = new Random();
  anotherModel(){

    //watch for changes in model instance properties
    this.model.changes.listen((List<ChangeRecord> records) {
      for(ChangeRecord change in records){
        print(change.toString());
      }
    });
  }

  //the callback for the timer to assign a random value model.x
  setModelProps(){
    model.x = rng.nextInt(100);
    print('called...');
  }
}

我正在使用引发notifyPropertyChange的setter来更改Model实例中属性的值,但它从未侦听更改,任何想法为何?

最佳答案

我认为您想使用ChangeNotifier而不是Observable

我不确定notifyPropertyChange,但是对于Observable,通常需要调用dirtyCheck以获得有关更改的通知。

前一阵子我做了一个小例子来学习这两个如何工作:

import 'package:observe/observe.dart';

class Notifiable extends Object with ChangeNotifier {
  String _input = '';

  @reflectable
  get input => _input;

  @reflectable
  set input(val) {
    _input = notifyPropertyChange(#input, _input, val + " new");
  }

  Notifiable() {
    this.changes.listen((List<ChangeRecord> record) => record.forEach(print));
  }
}

class MyObservable extends Observable {
  @observable
  String counter = '';

  MyObservable() {
    this.changes.listen((List<ChangeRecord> record) => record.forEach(print));
  }
}

void main() {
  var x = new MyObservable();
  x.counter = "hallo";
  Observable.dirtyCheck();

  Notifiable notifiable = new Notifiable();
  notifiable.input = 'xxx';
  notifiable.input = 'yyy';
}

10-06 12:53