如何使用 angular 4 从父元素获取子元素 DOM 引用

Question

我需要使用 angular 4 从父组件获取子组件 DOM 引用，但我无法访问子组件 DOM，请指导我如何实现此目的.

parent.component.html

<child-component></child-component>

parent.component.ts

import { Component, Input, ViewChild, ElementRef, AfterViewInit } from '@angular/core';

@Component({
  selector: 'parent-component',
  templateUrl: './parent.component.html'
})
export class ParentComponent implements AfterViewInit {
  @ViewChild('tableBody') tableBody: ElementRef;
  constructor(){
    console.log(this.tableBody);//undefined
  }
  ngAfterViewInit() {
       console.log(this.tableBody);//undefined
   }
}

child.component.ts

import { Component } from '@angular/core';
@Component({
  selector: 'child-component',
  templateUrl: './child.component.html'
})
export class ChildComponent { 
}

child.component.html

<div>
        <table border="1">
      <th>Name</th>
      <th>Age</th>
      <tbody #tableBody>
        <tr>
         <td>ABCD</td>
          <td>12</td>
        </tr>        
      </tbody>
        </table>
</div>

Answer 1

需要从父组件引用 tableBody。所以将它添加到 child-component 并将其从 tbody

中删除

<child-component #tableBody></child-component>

Answer 2

要扩展 Sachila Ranawaka 的回答：

首先你需要<child-component #childComp></child-component>

在你的父组件中，而不是 ElementRef 它应该是 ChildComponent:

@Component({
  selector: 'parent-component',
  templateUrl: './parent.component.html'
})
export class ParentComponent implements AfterViewInit {
  @ViewChild('childComp') childComp: ChildComponent;
  constructor(){
  }
  ngAfterViewInit() {
    console.log(this.childComp.tableBody);
  }
}

对于您的子组件：

@Component({
  selector: 'child-component',
  templateUrl: './child.component.html'
})
export class ChildComponent { 
  @ViewChild('tableBody') tableBody: ElementRef;
}

Answer 3

除了 Sachila 和 penleychan 的好答案之外，您还可以仅通过其组件名称来引用具有 @ViewChild 的组件：

parent.component.html

<!-- You don't need to template reference variable on component -->   
<child-component></child-component>

然后在parent.component.ts

import { ChildComponent } from './child-component-path';

@Component({
  selector: 'parent-component',
  templateUrl: './parent.component.html'
})
export class ParentComponent implements AfterViewInit {
  @ViewChild(ChildComponent) childComp: ChildComponent;
  constructor(){
  }
  ngAfterViewInit() {
    console.log(this.childComp.tableBody);
  }
}

如何使用 angular 4 从父元素获取子元素 DOM 引用

How to get the child DOM element reference from Parent using angular 4

angular-components

angular