角在父上使用指令获取嵌套元素 [英] Angular get nested element using directive on parent

问题描述

这是我拥有的代码

<parent my-directive [toHide]="childRef">

 <child bottom right #childRef>
    <button>Some text </button>
 </child >

</parent >

在这里，我在父元素上有my-directive，我想访问该子元素并对其应用某种样式.

Here I have my-directive on the parent element and I want to access the child and apply some style to it.

所以在我的指令中，我有以下内容.

So in my directive, I have the following.

export class MyDirective {
  @Input("toHide") localRef;

  constructor(public element:ElementRef,public renderer:Renderer) {
    console.log('Hello MyDirective Directive');
  }

  ngAfterViewInit() {
    console.log("All Transtition set");
    console.log(this.localRef);
this.renderer.setElementStyle(this.localRef, 'webkitTransition', 'transform 500ms,top 500ms');
  }

如您所见，我正在使用this.renderer设置元素的样式，但得到了以下内容.

As you can see that I am using this.renderer to set the style on the element but I get the following.

ERROR Error: Uncaught (in promise): TypeError: el.style is undefined

在这方面的任何帮助都是值得的.

Any help in this regard is appritiated.

推荐答案

如果<child>是纯HTML元素(无组件)，则它应该可以工作(添加了nativeElement)

If <child> is a plain HTML element (no component) then this should work (added nativeElement)

this.renderer.setElementStyle(
    this.localRef.nativeElement, 'webkitTransition', 'transform 500ms,top 500ms');

如果<child>是Angular组件，请更改此行

if <child> is an Angular component change this line

@Input("toHide") localRef;

到

@ContentChild('childRef', { read: ElementRef }) localRef;

并删除[toHide] ="childRef"

and remove [toHide]="childRef"

如果元素具有模板变量 是一个普通的HTML元素，读取引用将返回ElementRef，并且可以使用nativeElement属性访问实际元素.

If an element with a template variable is a plain HTML element, reading the reference returns an ElementRef and the actual element can be accessed using the nativeElement property.

如果它是组件或承载指令，则读取引用将返回不能用于访问DOM元素的组件或指令实例.

If it is a component or hosts a directive, reading the reference returns the component or directive instance which can't be used to access the DOM element.

@ViewChild(ren)和@ContentChild(ren)允许使用read参数指定要从模板变量引用中返回的内容，但是从模板内部访问模板变量引用则不提供该功能.

@ViewChild(ren) and @ContentChild(ren) allow to specify what to return from the template variable reference using the read parameter, but accessing the template variable reference from within the template doesn't provide that.

但是我建议使用

@HostBinding('class.is-transition')
isTransition:boolean false;

在指令中并使用CSS之类的

in the directive and use CSS like

parent[host-directive] > child {
  -webkit-transition: transform 500ms,top 500ms;
}

以应用样式.

这篇关于角在父上使用指令获取嵌套元素的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！