通过angular中的指令访问模板变量 [英] Access template variables through directive in angular

问题描述

我目前正在研究仅操作dom元素的指令.

I am currently working on a directive which simply manipulates the dom elements.

我想访问作为指令宿主的元素的模板变量，但由于结果始终是不确定的，因此我无法执行此操作.

I wanted to access to template variables of the element which is the host of the directive, but I was unable to do that, because the result is always undefined.

指令:

@Directive({
    selector: '[sample-directive]'
})
export class SampleDirective implements AfterViewInit {
    @ViewChild('queryMe') queryMe: ElementRef;

    ngAfterViewInit(): void {
        console.log(this.queryMe);    
    }
}

sampleComponent.template.html:

sampleComponent.template.html:

<div #queryMe></div>

用法:

<sample-component [sample-directive]></sample-component>

是否可以使用这样的模板变量?

Is it possible to use template variables like that?

推荐答案

将模板变量发送到指令:

Send the template variables over to your directive : stackblitz

@Input('appQuery') appQuery: HTMLElement;

<div [appQuery]="queryMe">
  <div #queryMe></div>
</div>

编辑

第二个解决方案:为您的可查询元素提供自定义属性.由于模板变量只是对HTML元素的引用，因此您将获得几乎相同的结果(除了标签中的另一个属性).

EDIT

Second solution : provide custom attributes to your query-able elements. Since template variables are just references to HTML elements, you will get pretty much the same result (except for one more attribute in your tag).

Stackblitz

get element() { return this.el.nativeElement; }
ngAfterViewInit() {
  console.log(this.element.querySelector('[queryMe]'));
}

<div appQuery>
  <div queryMe></div>
</div>

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