如何在Angular 6中从父组件调用子组件的方法

Question

父组件

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

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

    submit(): void {
        // execute child component method
        // This line is compiled properly but at the run time it gives me error related to the static injector## Heading ##
        childComp.callMethod();
    }
}

子组件

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

@Component({
    selector: 'child',
    template: '<h3>Child component {{test}}</h3>'
})
export class ChildComponent implements OnInit {
   test:string; 
   constructor() { }

    ngOnInit() { }

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

我在使用静态注入器时遇到错误，无法在父组件中注入子组件。这是错误。

StaticInjectorError（AppModule）[AppComponent-> ChildComponent]：StaticInjectorError [ChildComponet]：NullInjectorError：没有为ChildComponet提供程序！

我在Appmodule中添加了引用，并在声明中添加了组件。不过，我也面临着同样的问题。

请帮忙！！

Answer 1

更新：

只需将like导出为子对象<app-child #child></app-child>，然后可以使用childlike 调用所有方法：<button> (click)="child.callMethod()">Call</button>

Parent.html

<app-child #child></app-child>
<button (click)="child.callMethod()">Call</button>

旧答案

您可以@ViewChild像以下示例一样由Parent 使用：

父级

import { Component, ViewChild } from '@angular/core';
import { ChildComponent } from './child.component';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  constructor() { }
  @ViewChild(ChildComponent) private myChild: ChildComponent;
  submit() {
    this.myChild.callMethod();
  }
}

儿童：

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

@Component({
  selector: 'child',
  template: `<h3>Child component {{test}}</h3>`
})
export class ChildComponent {
  test = 0;
  callMethod() {
    console.log('successfully executed.');
    this.test++;
  }
}

这是一个可行的例子