您可以获得组件封装主机ID吗? [英] Can you get the component encapsulation host ID?

问题描述

有没有办法获取赋予组件的封装主机ID?

Is there a way to get the encapsulation host id that is given to a component?

如果您有使用ViewEncapsulation.Emulated的组件，则 DOM 中的元素将具有类似_nghost-par-2.的属性名称，即唯一ID 赋予组件以封装相关的样式.

If you have a component that is using ViewEncapsulation.Emulated the element in the DOM will have an attribute name of something like _nghost-par-2. Which, is a unique ID given to the component to encapsulate the associated styles.

如何获取该ID作为组件的构造函数的一部分?

How do you get that ID as part of the component's constructor?

以下方面的作用:

@Component({
  hostId:string;
  ...
})
export class myComponent implements OnInit {
  constructor(host:Host) {
    this.hostId = host.id;
  }
  ...
}

推荐答案

此ID由以下部分组成:

This ID consists of the following parts:

_nghost   -   par    -     2
   |           |           |
 static      APP_ID   _nextCompTypeId

APP_ID 是来自@ angular/core的公正令牌

APP_ID is a just token from @angular/core

如果您需要避免将随机生成的值用作 应用程序ID，您可以通过DI提供程序提供自定义值 使用此令牌配置根注入器

If you need to avoid randomly generated value to be used as an application id, you can provide a custom value via a DI provider configuring the root Injector using this token

_nextCompTypeId 是在私有类ViewUtils中的框架内部生成的.

_nextCompTypeId is generated inside framework within private class ViewUtils.

似乎没有公共方法可以返回其值.因此，以下方法可能会起作用

Seems there is no a public method which can return it value. So probably the following will work

export class MyComponent { 
  id: string;
  constructor(@Inject(APP_ID) appId: string, vcRef: ViewContainerRef) {
    this.id = `${appId}-${vcRef.injector['_view'].viewUtils._nextCompTypeId - 1}`;
  }
}

另一种方法是通过elementRef

如果您使用的是 Angular 9 ，请按照此答案

If you're on Angular 9 then follow this answer How to access components unique encapsulation ID in Angular 9

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