Angular2子属性更改未在绑定属性上触发更新

Question

我有一个带有输入的简单自定义指令,我在我的组件中绑定.但无论出于何种原因,更改输入属性的子属性时都不会触发ngOnchanges()方法.

my.component.ts

import {Component} from 'angular2/core';
import {MyDirective} from './my.directive';

@Component({
    directives: [MyDirective],
    selector: 'my-component', 
    templateUrl: 'Template.html'
})

export class MyComponent {
    test: { one: string; } = { one: "1" }

    constructor( ) {
        this.test.one = "2";
    }
    clicked() {
        console.log("clicked");
        var test2: { one: string; } = { one :"3" };
        this.test = test2; // THIS WORKS - because I'm changing the entire object
        this.test.one = "4"; //THIS DOES NOT WORK - ngOnChanges is NOT fired=
    }
}

my.directive.ts

import {Directive, Input} from 'angular2/core';
import {OnChanges} from 'angular2/core';

@Directive({
    selector: '[my-directive]',
    inputs: ['test']
})

export class MyDirective implements OnChanges {
    test: { one: string; } = { one: "" }

    constructor() { }

    ngOnChanges(value) {
        console.log(value);
    }
}

template.html

<div (click)="clicked()"> Click to change </div>
<div my-directive [(test)]="test">

谁能告诉我为什么？

Answer 1

事实上,这是一种正常的行为,Angular2不支持深度比较.它仅基于参考比较.请参阅此问题:https://github.com/angular/angular/issues/6458.

这表示他们是一些解决方法,通知指令对象中的某些字段已更新.

• 引用组件中的指令

  export class AppComponent {
    test: { one: string; } = { one: '1' }
    @ViewChild(MyDirective) viewChild:MyDirective;
  
    clicked() {
      this.test.one = '4';
      this.viewChild.testChanged(this.test);
    }
  }
  

  在这种情况下,显式调用指令的testChanged方法.请参阅此plunkr:https://plnkr.co/edit/TvibzkWUKNxH6uGkL6mJ ？ p = preview .

• 使用服务中的事件

  专用服务定义testChanged事件

  export class ChangeService {
    testChanged: EventEmitter;
  
    constructor() {
      this.testChanged = new EventEmitter();
    }
  }
  

  该组件使用服务来触发testChanged事件:

  export class AppComponent {
    constructor(service:ChangeService) {
      this.service = service;
    }
  
    clicked() {
      this.test.one = '4';
      this.service.testChanged.emit(this.test);
    }
  }
  

  该指令订阅此testChanged事件以便得到通知

  export class MyDirective implements OnChanges,OnInit {
    @Input()
    test: { one: string; } = { one: "" }
  
    constructor(service:ChangeService) {
      service.testChanged.subscribe(data => {
        console.log('test object updated!');
      });
    }
  }
  

希望它对你有帮助,蒂埃里