从父类- Angular调用子组件方法

我已经创建了一个子组件，其中有一个我想调用的方法。

当我调用这个方法时，它只会触发console.log()行，它不会设置测试属性??

下面是我修改后的Angular快速入门应用。

父

import { Component } from '@angular/core';
import { NotifyComponent }  from './notify.component';

@Component({
    selector: 'my-app',
    template:
    `
    <button (click)="submit()">Call Child Component Method</button>
    `
})
export class AppComponent {
    private notify: NotifyComponent;

    constructor() { 
      this.notify = new NotifyComponent();
    }

    submit(): void {
        // execute child component method
        notify.callMethod();
    }
}

孩子

import { Component, OnInit } from '@angular/core';

@Component({
    selector: 'notify',
    template: '<h3>Notify {{test}}</h3>'
})
export class NotifyComponent implements OnInit {
   test:string; 
   constructor() { }

    ngOnInit() { }

    callMethod(): void {
        console.log('successfully executed.');
        this.test = 'Me';
    }
}

我如何设置测试属性以及?

当前回答

我认为最简单的方法是使用Subject。在下面的示例代码中，每次调用'tellChild()'时都会通知子进程。

Parent.component.ts

import {Subject} from 'rxjs/Subject';
...
export class ParentComp {
  changingValue: Subject<boolean> = new Subject();
        
  tellChild() {
    this.changingValue.next(true);
  }
}

Parent.component.html

<my-comp [changing]="changingValue"></my-comp>

Child.component.ts

...
export class ChildComp implements OnInit{
  @Input() changing: Subject<boolean>;
  
  ngOnInit(){
    this.changing.subscribe(v => { 
      console.log('value is changing', v);
    });
  }
}

斯塔克布利茨的工作样本

2018-05-10 20:44:57

其他回答

parent.component.html

<app-child #childComponent></app-child>

parent.component.ts

@Component({
    selector: 'app-parent',
    templateUrl: './app-parent.component.html',
    styleUrls: ['./app-parent.component.scss']
})
export class ParentComponent {
    @ViewChild('childComponent', {static: false}) childComponent: ChildComponent;

    anyMethod(): void {
        childComponent.updateData() // updateData is a child method
    }
}

child.component.ts

@Component({
    selector: 'app-child',
    templateUrl: './app-child.component.html',
    styleUrls: ['./app-child.component.scss']
})
export class ChildComponent {
    updateData(): void {
      // Method code goes here
    }
}

2021-11-26 11:19:13

Angular——在父组件模板中调用子组件的方法

你有像这样的ParentComponent和ChildComponent。

parent.component.html

parent.component.ts

import {Component} from '@angular/core';

@Component({
  selector: 'app-parent',
  templateUrl: './parent.component.html',
  styleUrls: ['./parent.component.css']
})
export class ParentComponent {
  constructor() {
  }
}

child.component.html

<p>
  This is child
</p>

child.component.ts

import {Component} from '@angular/core';

@Component({
  selector: 'app-child',
  templateUrl: './child.component.html',
  styleUrls: ['./child.component.css']
})
export class ChildComponent {
  constructor() {
  }

  doSomething() {
    console.log('do something');
  }
}

发球时，是这样的:

当用户关注ParentComponent的input元素时，你需要调用ChildComponent的doSomething()方法。

简单地这样做:

给parent.component.html中的app-child selector一个DOM变量名 (前缀# -标签)，在这种情况下，我们称之为appChild。将表达式值(要调用的方法的值)赋给输入元素的焦点事件。

结果:

2019-06-13 11:30:46

考虑下面的例子:

import import { AfterViewInit, ViewChild } from '@angular/core';
import { Component } from '@angular/core';
import { CountdownTimerComponent }  from './countdown-timer.component';

@Component({
    selector: 'app-countdown-parent-vc',
    templateUrl: 'app-countdown-parent-vc.html',
    styleUrl: [app-countdown-parent-vc.css]
})
export class CreateCategoryComponent implements OnInit, AfterViewInit {
    @ViewChild(CountdownTimerComponent, {static: false}) private timerComponent: CountdownTimerComponent;
    ngAfterViewInit() {
        this.timerComponent.startTimer();
    }

    submitNewCategory(){
        this.ngAfterViewInit();
    }
}

点击这里阅读更多关于@ViewChild的信息。

2019-11-02 11:33:32

这对我很管用!对于Angular 2，在父组件中调用子组件方法

Parent.component.ts

    import { Component, OnInit, ViewChild } from '@angular/core';
    import { ChildComponent } from '../child/child'; 
    @Component({ 
               selector: 'parent-app', 
               template: `<child-cmp></child-cmp>` 
              }) 
    export class parentComponent implements OnInit{ 
        @ViewChild(ChildComponent ) child: ChildComponent ; 

        ngOnInit() { 
           this.child.ChildTestCmp(); } 
}

Child.component.ts

import { Component } from '@angular/core';
@Component({ 
  selector: 'child-cmp', 
  template: `<h2> Show Child Component</h2><br/><p> {{test }}</p> ` 
})
export class ChildComponent {
  test: string;
  ChildTestCmp() 
  { 
    this.test = "I am child component!"; 
  }
 }

2017-07-04 14:29:32

User6779899的答案简洁且更通用但是，根据Imad El Hitti的要求，这里提出了一种轻量级的解决方案。当子组件仅与一个父组件紧密连接时，可以使用此选项。

Parent.component.ts

export class Notifier {
    valueChanged: (data: number) => void = (d: number) => { };
}

export class Parent {
    notifyObj = new Notifier();
    tellChild(newValue: number) {
        this.notifyObj.valueChanged(newValue); // inform child
    }
}

Parent.component.html

<my-child-comp [notify]="notifyObj"></my-child-comp>

Child.component.ts

export class ChildComp implements OnInit{
    @Input() notify = new Notifier(); // create object to satisfy typescript
    ngOnInit(){
      this.notify.valueChanged = (d: number) => {
            console.log(`Parent has notified changes to ${d}`);
            // do something with the new value 
        };
    }
 }

2019-01-28 10:54:48

从父类- Angular调用子组件方法

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