Angular:如何访问 ng-template 中的引用变量 [英] Angular: how do I access the reference variable which is in a ng-template

问题描述

有没有办法访问#interface，它在ng-template元素中声明?

Is there a way to access #interface, which is declared inside ng-template element?

我必须将 <interface-settings 放在 <ng-template 中.

I must put the <interface-settings inside <ng-template.

因为我需要使用 *ngTemplateOutlet.

Because I would need to use the *ngTemplateOutlet.

由于我找不到解决方案，我必须添加另一个 <interface-settings #interface 并且不在 ng-template 中声明它.

As I could not find a solution for this, I have to add another <interface-settings #interface and not declare it inside ng-template.

如果您知道其他解决方法，我们将不胜感激.谢谢

would appreciate if you know other workaround. Thanks

 //  parent.html
 <button type="button" (click)="interface.apply()"></button>

 <ng-template>
    <interface-settings #interface></interface-settings>
 <ng-template>

---

 //child.ts (interface-settings.ts)

apply() {
   console.log("apply");
 }

推荐答案

ng-template 被 Angular 用于模板化 - 这意味着它不会在 DOM 中呈现，除非某些条件告诉 Angular 在实际的 DOM 中使用它.

ng-template is used by Angular for templating - meaning it is not rendered in DOM unless certain conditions tell Angular to use it in the actual DOM.

所以当你有你的组件界面设置"时在 ng-template 中 - 您的应用程序无法访问/知道它，除非:

So when you have your component "interface-setting" inside ng-template - it is not accessible/known by your application unless:

• 应用了 ng-template 条件并且
• 您的主机(父)组件引用了它:

例如，类似于您的示例:

For instance, similar to your example:

<button type="button" (click)="hello.sayHello()">Method Inside Hello</button>

<ng-template>
  <hello #hello></hello>
<ng-template>

由于不满足上述 2 个条件，因此上述内容本身不起作用.要修复，您需要使用 ViewChild 来获取对 hello 组件的引用.像这样:

The above on its own won't work as 2 conditions mentioned above are not met. To fix you need to use ViewChild to get reference to the hello component. Like so:

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {

  @ViewChild('hello') hello;

}

然后你需要确保使用了 ng-template(无论是什么触发了 ng-template 被放置在你的应用程序的 DOM 中):

Then you need to make sure the ng-template is used (whatever triggers the ng-template to be placed in DOM for your app):

<ng-template [ngIf]="true">
  <hello #hello></hello>
<ng-template>

现在对子组件内部方法的引用将起作用:

Now the reference to the method inside child component will work:

https://stackblitz.com/edit/angular-ivy-hnmw17?file=src/app/app.component.html

您可以阅读更多 Angular 的结构指令如何使用 ng-template:https://angular.io/guide/structural-directives

You can read more how Angular's structural directives under the hood use ng-template: https://angular.io/guide/structural-directives

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