Angular中没有等价的$scope.emit()或$scope.broadcast()吗?

我知道EventEmitter功能,但据我所知,它只会向父HTML元素发出一个事件。

如果我需要在fx和。还是DOM根组件和嵌套了几层的元素之间?


当前回答

我们实现了一个ngModelChange可观察指令,它通过你在自己的组件中实例化的事件发射器发送所有模型更改。您只需将事件发射器绑定到该指令。

参见:https://github.com/atomicbits/angular2-modelchangeobservable

在html中,绑定你的事件发射器(本例中为countryChanged):

<input [(ngModel)]="country.name"
       [modelChangeObservable]="countryChanged" 
       placeholder="Country"
       name="country" id="country"></input>

在你的typescript组件中,对EventEmitter执行一些异步操作:

import ...
import {ModelChangeObservable} from './model-change-observable.directive'


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

export class MyComponent {

    @Input()
    country: Country

    selectedCountries:Country[]
    countries:Country[] = <Country[]>[]
    countryChanged:EventEmitter<string> = new EventEmitter<string>()


    constructor() {

        this.countryChanged
            .filter((text:string) => text.length > 2)
            .debounceTime(300)
            .subscribe((countryName:string) => {
                let query = new RegExp(countryName, 'ig')
                this.selectedCountries = this.countries.filter((country:Country) => {
                    return query.test(country.name)
                })
            })
    }
}

其他回答

我最喜欢的方法是在我的服务中使用行为主题或事件发射器(几乎相同)来控制我的所有子组件。

使用angular cli,运行ng gs来创建一个新的服务,然后使用BehaviorSubject或EventEmitter

export Class myService {
#all the stuff that must exist

myString: string[] = [];
contactChange : BehaviorSubject<string[]> = new BehaviorSubject(this.myString);

   getContacts(newContacts) {
     // get your data from a webservices & when you done simply next the value 
    this.contactChange.next(newContacts);
   }
}

当您这样做时,作为提供者使用您的服务的每个组件都将知道更改。只需订阅结果,就像你用eventEmitter;)

export Class myComp {
#all the stuff that exists like @Component + constructor using (private myService: myService)

this.myService.contactChange.subscribe((contacts) => {
     this.contactList += contacts; //run everytime next is called
  }
}

您可以使用EventEmitter或可观察对象来创建向DI注册的事件总线服务。每个想要参与的组件只需将服务作为构造函数参数请求,并发出和/或订阅事件。

另请参阅

https://angular.io/docs/ts/latest/cookbook/component-communication.html !# bidirectional-service 委托:在Angular2中的EventEmitter或Observable

我在这里创建了一个pub-sub示例:

http://www.syntaxsuccess.com/viewarticle/pub-sub-in-angular-2.0

这个想法是使用RxJs subject来连接一个观察者和和可观察对象,作为一个通用的解决方案来发送和订阅自定义事件。在我的示例中,出于演示目的,我使用了一个customer对象

this.pubSubService.Stream.emit(customer);

this.pubSubService.Stream.subscribe(customer => this.processCustomer(customer));

这里还有一个现场演示: http://www.syntaxsuccess.com/angular-2-samples/#/demo/pub-sub

我们实现了一个ngModelChange可观察指令,它通过你在自己的组件中实例化的事件发射器发送所有模型更改。您只需将事件发射器绑定到该指令。

参见:https://github.com/atomicbits/angular2-modelchangeobservable

在html中,绑定你的事件发射器(本例中为countryChanged):

<input [(ngModel)]="country.name"
       [modelChangeObservable]="countryChanged" 
       placeholder="Country"
       name="country" id="country"></input>

在你的typescript组件中,对EventEmitter执行一些异步操作:

import ...
import {ModelChangeObservable} from './model-change-observable.directive'


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

export class MyComponent {

    @Input()
    country: Country

    selectedCountries:Country[]
    countries:Country[] = <Country[]>[]
    countryChanged:EventEmitter<string> = new EventEmitter<string>()


    constructor() {

        this.countryChanged
            .filter((text:string) => text.length > 2)
            .debounceTime(300)
            .subscribe((countryName:string) => {
                let query = new RegExp(countryName, 'ig')
                this.selectedCountries = this.countries.filter((country:Country) => {
                    return query.test(country.name)
                })
            })
    }
}

下面的代码是Angular 2中使用共享服务来处理事件的$scope.emit()或$scope.broadcast()的替换示例。

import {Injectable} from 'angular2/core';
import * as Rx from 'rxjs/Rx';

@Injectable()
export class EventsService {
    constructor() {
        this.listeners = {};
        this.eventsSubject = new Rx.Subject();

        this.events = Rx.Observable.from(this.eventsSubject);

        this.events.subscribe(
            ({name, args}) => {
                if (this.listeners[name]) {
                    for (let listener of this.listeners[name]) {
                        listener(...args);
                    }
                }
            });
    }

    on(name, listener) {
        if (!this.listeners[name]) {
            this.listeners[name] = [];
        }

        this.listeners[name].push(listener);
    }

    off(name, listener) {
        this.listeners[name] = this.listeners[name].filter(x => x != listener);
    }

    broadcast(name, ...args) {
        this.eventsSubject.next({
            name,
            args
        });
    }
}

使用示例:

广播:

function handleHttpError(error) {
    this.eventsService.broadcast('http-error', error);
    return ( Rx.Observable.throw(error) );
}

听众:

import {Inject, Injectable} from "angular2/core";
import {EventsService}      from './events.service';

@Injectable()
export class HttpErrorHandler {
    constructor(eventsService) {
        this.eventsService = eventsService;
    }

    static get parameters() {
        return [new Inject(EventsService)];
    }

    init() {
        this.eventsService.on('http-error', function(error) {
            console.group("HttpErrorHandler");
            console.log(error.status, "status code detected.");
            console.dir(error);
            console.groupEnd();
        });
    }
}

它可以支持多个参数:

this.eventsService.broadcast('something', "Am I a?", "Should be b", "C?");

this.eventsService.on('something', function (a, b, c) {
   console.log(a, b, c);
});