[英]Emit event from parent to child
我button in the parent component namely
有一个Submit button in the parent component namely
personDetails .
personDetails has many
人的组件。 每当我点击Submit按钮时,我想调用子组件中的方法。
如何使用@Output
从父组件向子组件发出事件?
它很容易从孩子到父母。 我想访问子组件的值,因此我需要从父级发送一个事件到子级。
您可以创建一个在父组件和子组件之间共享的服务,您可以在其中定义Observable
以便您可以从子组订阅该Observable
,并在从父级接收某些值时执行某些操作。
//common.service.ts
import { Injectable, Inject } from '@angular/core';
import { Subject } from 'rxjs/Subject';
@Injectable()
export class CommonService {
private notify = new Subject<any>();
/**
* Observable string streams
*/
notifyObservable$ = this.notify.asObservable();
constructor(){}
public notifyOther(data: any) {
if (data) {
this.notify.next(data);
}
}
}
//parent.component.ts
import { Component, OnInit, OnDestroy } from '@angular/core';
import { Subscription } from 'rxjs/Subscription';
import { CommonService } from './common.service';
@Component({
selector : 'parent',
templateUrl : './parent.html'
})
export class ParentComponent implements OnInit, OnDestroy {
constructor( private commonService: CommonService ){
}
ngOnInit() {
this.commonService.notifyOther({option: 'call_child', value: 'From child'});
}
}
//child.component.ts
import { Component, OnInit, OnDestroy } from '@angular/core';
import { Subscription } from 'rxjs/Subscription';
import { CommonService } from './common.service';
@Component({
selector : 'child',
templateUrl : './child.html'
})
export class ChildComponent implements OnInit, OnDestroy {
private subscription: Subscription;
constructor( private commonService: CommonService ){
}
ngOnInit() {
this.subscription = this.commonService.notifyObservable$.subscribe((res) => {
if (res.hasOwnProperty('option') && res.option === 'call_child') {
console.log(res.value);
// perform your other action from here
}
});
}
ngOnDestroy() {
this.subscription.unsubscribe();
}
}
在childComponent.ts
@Input() private uploadSuccess: EventEmitter<boolean>;
另外在childComponent.ts
订阅事件:
ngOnInit() {
if (this.uploadSuccess) {
this.uploadSuccess.subscribe(data => {
// Do something in the childComponent after parent emits the event.
});
}
}
在ParentComponent.html
<app-gallery [uploadSuccess] = "uploadSuccess" > </app-gallery>
在ParentComponent.ts
private uploadSuccess: EventEmitter<boolean> = new EventEmitter();
onImageUploadSuccess(event) {
console.log('Image Upload succes');
if (event.code === 'OK' && this.maxUploadLimit > 0) {
this.galleryImagesCount = this.galleryImagesCount + 1;
this.maxUploadLimit = this.maxUploadLimit - 1;
}
// The parent emits the event which was given as `@Input` variable to the child-component
this.uploadSuccess.emit(true);
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.