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?
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
其他回答
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)
})
})
}
}
我正在使用一个消息服务,包装rxjs主题(TypeScript)
Plunker示例:Message Service
import { Injectable } from '@angular/core';
import { Subject } from 'rxjs/Subject';
import { Subscription } from 'rxjs/Subscription';
import 'rxjs/add/operator/filter'
import 'rxjs/add/operator/map'
interface Message {
type: string;
payload: any;
}
type MessageCallback = (payload: any) => void;
@Injectable()
export class MessageService {
private handler = new Subject<Message>();
broadcast(type: string, payload: any) {
this.handler.next({ type, payload });
}
subscribe(type: string, callback: MessageCallback): Subscription {
return this.handler
.filter(message => message.type === type)
.map(message => message.payload)
.subscribe(callback);
}
}
组件可以订阅和广播事件(发送方):
import { Component, OnDestroy } from '@angular/core'
import { MessageService } from './message.service'
import { Subscription } from 'rxjs/Subscription'
@Component({
selector: 'sender',
template: ...
})
export class SenderComponent implements OnDestroy {
private subscription: Subscription;
private messages = [];
private messageNum = 0;
private name = 'sender'
constructor(private messageService: MessageService) {
this.subscription = messageService.subscribe(this.name, (payload) => {
this.messages.push(payload);
});
}
send() {
let payload = {
text: `Message ${++this.messageNum}`,
respondEvent: this.name
}
this.messageService.broadcast('receiver', payload);
}
clear() {
this.messages = [];
}
ngOnDestroy() {
this.subscription.unsubscribe();
}
}
(接收方)
import { Component, OnDestroy } from '@angular/core'
import { MessageService } from './message.service'
import { Subscription } from 'rxjs/Subscription'
@Component({
selector: 'receiver',
template: ...
})
export class ReceiverComponent implements OnDestroy {
private subscription: Subscription;
private messages = [];
constructor(private messageService: MessageService) {
this.subscription = messageService.subscribe('receiver', (payload) => {
this.messages.push(payload);
});
}
send(message: {text: string, respondEvent: string}) {
this.messageService.broadcast(message.respondEvent, message.text);
}
clear() {
this.messages = [];
}
ngOnDestroy() {
this.subscription.unsubscribe();
}
}
MessageService的subscribe方法返回一个rxjs订阅对象,可以像这样取消订阅:
import { Subscription } from 'rxjs/Subscription';
...
export class SomeListener {
subscription: Subscription;
constructor(private messageService: MessageService) {
this.subscription = messageService.subscribe('someMessage', (payload) => {
console.log(payload);
this.subscription.unsubscribe();
});
}
}
也可以看到这个答案:https://stackoverflow.com/a/36782616/1861779
Plunker示例:Message Service
不要使用EventEmitter来进行服务通信。
你应该使用Observable类型之一。我个人喜欢BehaviorSubject。
简单的例子:
你可以传递初始状态,这里我传递null
let subject = new BehaviorSubject(null);
当你想要更新主题时
next (myObject)科目。
观察任何服务或组件,并在其获得新的更新时采取行动。
subject.subscribe (this.YOURMETHOD);
这里有更多信息。
下面的代码是Angular 2中使用共享服务来处理事件的$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);
});
这是我的版本:
export interface IEventListenr extends OnDestroy{
ngOnDestroy(): void
}
@Injectable()
export class EventManagerService {
private listeners = {};
private subject = new EventEmitter();
private eventObserver = this.subject.asObservable();
constructor() {
this.eventObserver.subscribe(({name,args})=>{
if(this.listeners[name])
{
for(let listener of this.listeners[name])
{
listener.callback(args);
}
}
})
}
public registerEvent(eventName:string,eventListener:IEventListenr,callback:any)
{
if(!this.listeners[eventName])
this.listeners[eventName] = [];
let eventExist = false;
for(let listener of this.listeners[eventName])
{
if(listener.eventListener.constructor.name==eventListener.constructor.name)
{
eventExist = true;
break;
}
}
if(!eventExist)
{
this.listeners[eventName].push({eventListener,callback});
}
}
public unregisterEvent(eventName:string,eventListener:IEventListenr)
{
if(this.listeners[eventName])
{
for(let i = 0; i<this.listeners[eventName].length;i++)
{
if(this.listeners[eventName][i].eventListener.constructor.name==eventListener.constructor.name)
{
this.listeners[eventName].splice(i, 1);
break;
}
}
}
}
emit(name:string,...args:any[])
{
this.subject.next({name,args});
}
}
use:
export class <YOURCOMPONENT> implements IEventListener{
constructor(private eventManager: EventManagerService) {
this.eventManager.registerEvent('EVENT_NAME',this,(args:any)=>{
....
})
}
ngOnDestroy(): void {
this.eventManager.unregisterEvent('closeModal',this)
}
}
发出:
this.eventManager.emit("EVENT_NAME");