将嵌套组件孙子之间的事件发送到根组件 [英] Emit events between nested components grandchild to root component

问题描述

我有 wheels.component 嵌套到 car.component 。

wheels.component：

export class WheelsComponent {    
    @Output() onLoaded : EventEmitter<string>() = new EventEmitter<string>();

    private downloadAllFiles(url: string) {
        this.onLoaded.emit('Hello, World 1!');
        //some operations to wait
        this.onLoaded.emit('Hello, World 2!');

    };
}

组件 car.component 不是在html页面写的，而是通过 car-routing.module.ts的路由调用：

Component car.component is not written at html page, but called through routing at car-routing.module.ts:

@NgModule({
    imports: [
        RouterModule.forChild([
            {
                path: 'sfactmessage/:id',
                component: CarComponent,
                resolve: {
                    card: cardResolver
                }
            }
        ])
    ],
    exports: [RouterModule]
})
export class CarRoutingModule {}

我想要的是处理从<$ c $发出的事件c> wheels.component ，而不是 car.component ，但是在app.component 。

What I want is to handle event emitted from wheels.component, not at car.component, but at app.component.

是否可以在 app.component 处理事件？

< a href =http://plnkr.co/edit/EsEJw7jbkRw4aNJ9iJR0?p=preview&open=app%2Fapp.component.ts =nofoll ow noreferrer> plunker示例无效（抱歉，这是我的第一个plunkr示例），但是给出了我的应用程序如何安排的视图。

The plunker sample is not working (sorry, this is my first plunkr example), but gives a view how my app is arranged.

推荐答案

Hello_ friend。

Hello_ friend.

所以基本上如果你想在你的应用程序中全局使用事件，你可以使用服务与 EventEmitter

So basically if you want to use events globally in your application you can use a Service in combination with EventEmitter

在这种情况下，您创建一个服务，例如 car.service.ts

In this case you create a service for example car.service.ts

import { Injectable, EventEmitter } from '@angular/core';
@Injectable()
export class CarService {
  onLoaded : EventEmitter<string> = new EventEmitter<string>();
}

然后在子组件中使用此服务来发出这样的事件 wheels.component.ts

Then use this service in a child component to emit events like this wheels.component.ts

import { Component, EventEmitter } from '@angular/core';
import { CarService }  from './car.service';
@Component({
    selector: 'wheels',
    template: '<a (click)="sendValues()"> Click me to send value </a>'
})
export class WheelsComponent {

    constructor(private carService:CarService ){}

    sendValues() {
       /* Use service to emit events that can be used everywhere in the application */
        this.carService.onLoaded.emit('Button in WheelsComponent was clicked ...');
    }; 
}

然后从 AppComponent 捕获此事件，例如 app.component.ts

and then capture this event from AppComponent for example app.component.ts

import { Component, OnInit, OnDestroy } from '@angular/core';
import { CarService }  from './cars/car.service';
import { Subscription }  from 'rxjs';

@Component({
  selector: 'my-app',
  templateUrl: `src/app.component.html`
})
export class AppComponent implements OnInit, OnDestroy{ 
  private subscription: Subscription;
  private loading = true;
  name = 'Angular'; 

  constructor(private carService: CarService){} 

  ngOnInit(){
    this.subscription = this.carService.onLoaded.subscribe((message) => {

      /*
        Here you receive events from anywhere where
        carService.onLoaded.emit() is used
      **/

        alert(`From AppComponent -> ${message}`);
    });
  } 

  ngOnDestroy(){
    /* Don't forget to unsubscribe when component is destroyed */
    this.subscription.unsubscribe();
  }
}

IMPORTAN T ______________

如果您希望自己的服务全球，您需要在顶级提供商中声明它，例如 app.module.ts 是个好地方：

If you want your service to work globally you need to declare it in the top level providers for example app.module.ts is a good place:

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { AppComponent }  from './app.component';
import { CarComponent} from './cars/car.component';
import { WheelsComponent} from './cars/wheels.component';
import { HomeComponent} from './home.component';
import { routing }  from './app.routing';
import { CarService }  from './cars/car.service';

@NgModule({
  imports: [ BrowserModule, FormsModule, routing ],
  declarations: [ AppComponent, CarComponent, WheelsComponent, HomeComponent ],
  providers: [ CarService ], // <-------- SEE HERE
  bootstrap: [ AppComponent ]
})
export class AppModule { }

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