Angular2 +如何让孩子从父母那里得到通知

Question

对于Angular2 +，我们可以使用@output通知父对象，是否有任何方法可以让孩子知道在发出Child事件之前或之后调用了哪个父函数？

下面是父HTML代码，它将调用子组件以执行onClick或OnClose函数。

<child-comp (test1)="onClick()">
    ...
</child-comp>

<child-comp (test2)="onClose()">
    ...
</child-comp>

以下是子代码。

@Component({
    selector: 'child-comp'
})

export class ChildComponent{
    @Output() test1: EventEmitter<any> = new EventEmitter();
    @Output() test2: EventEmitter<any> = new EventEmitter();

    handleClick() {
        //this.test1.emit("test1 is emitted");
        //or 
        //this.test2.emit("test2 is emitted");

    }
}

问题是test1和test2都在handleClick函数中，一旦发出test1或test2事件，如何让孩子知道执行哪个父函数？

Answer 1

向子项添加一个@Input（）属性whatHappendInParent，并编写如下内容：

<child-comp (test1)="onClick()" [whatHappenedInParent] = whatHappened>
    ...
</child-comp>

<child-comp (test2)="onClose()" [whatHappenedInParent] = whatHappened>
    ...
</child-comp>
...
export class myParent {
  whatHappened: string;
  onClick(){
   this.whatHappened = "onClick was called";
  }
  onClose(){
   this.whatHappened = "onClose was called";
  }
}