如何在 Angular 2 中将事件从深层嵌套的子级传递给父级? [英] How pass a event from deep nested child to parent in Angular 2?

问题描述

我有一个嵌套的子组件，它有一个输出事件，我想从父组件监听这个事件，但我不知道怎么做，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:

我尝试将事件从孩子 3 传递给孩子 2，将孩子 2 传递给孩子和家长，但我认为这不是最好的方式.

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

Source Dan Wahlin (ng-conf: Mastering the Subject: Communication Options in RxJS ), 不建议使用 OutPut有一个更深层次的组件必须与更高级别的组件通信，假设您有 5 或 6 个级别！！，您必须使用 Subject 代替:您可以通过可观察服务创建事件总线

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

这里的事件是事件的枚举，如果你愿意的话

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 发出一个事件，例如在付款完成后 => 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));
  }
}

现在在你的父组件中你可以调用这样的方法，你会得到事件

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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