如何在Angular 2中将事件从深层嵌套子级传递给父级?

问题描述

我有一个带有输出事件的嵌套子组件，我想从父组件监听此事件，但我不知道如何，我有4个级别:

I have a nested child component that have a output Event, I want listen this event from parent component but I dont know how, I have 4 levels:

我试图将事件从孩子3传递给孩子2，将孩子2传递给孩子并传递给父母，但是我认为这不是最好的方法.

I tried to pass the event from child 3 to child 2 and child 2 to child and to Parent, but I think that this is not the best way.

-Parent (From this I want listen the event)
--Child
----Child 2
------Child 3 (This have the Event)

推荐答案

来源 Dan Wahlin (ng-conf:掌握主题:RxJS中的通信选项)，当您使用OUTPUT时，不建议使用有一个更深层次的组件，它必须与更高层次的杠杆组件进行通信，假设您有5个或6个级别！，您必须改用 Subject :您可以通过可观察的服务创建和事件总线

Source Dan Wahlin (ng-conf: Mastering the Subject: Communication Options in RxJS ), it's not recommanded to use OutPut when you have a component in a deeper level that has to communicate with a higher lever component , imagine you have 5 or 6 leves!!, you have to use Subject instead:you can create and Event bus through an observable service

事件如果需要，这里是事件的枚举

Events here is an enum of events if you want

export enum Events{
 'payment done',
  // other events here
 }

@Injectable()
export class EventService {

 private subject$ = new Subject()

 emit(event: EmitEvent) {
    this.subject$.next(event);
  }

 on(event: Events, action: any): Subscription {
 return this.subject$.pipe(
  filter((e: EmitEvent) => e.name == event),
  map((e: EmitEvent) => e.value)).subscribe(action);
 }

}

现在假设您想从 Child3 发出事件，例如，在付款后=>通知父组件

so now imagine that you want to emit an event from Child3 , let's say for example after a payment is done => notify parent component

export class Child3Component implements OnInit {

  constructor(public eventservice : EventService ) {}
  pay(paymentAmount: any) {
    this.eventservice.emit(
      new EmitEvent('payment done',paymentAmount));
  }
}

现在在您的父组件中，您可以调用这样的方法，您将获得事件

now in your parent component you can call on method like this and you will get the event

 export class ParentComponent implements OnInit {
   constructor(public eventservice : EventService ) {}
   ngOnInit() {
    this.eventservice.on('payment done', (paymentAmount => console.log(paymentAmount));
   }
 }

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