Angular 2从父级调用子级组件方法 [英] Angular 2 calling a child component method from the parent

问题描述

我尝试使用StackOverflow中建议的不同方法，但无法进行以下工作.

I have tried to use different methods suggested in StackOverflow but I cannot make the following work.

我在ParentComponent中有一个嵌套的ChildComponent.

I have a nested ChildComponent into a ParentComponent.

以下是父级的HTML:

Here the HTML of the parent:

<div> ... <div>

<span *ngIf="value" class="option-button cursor-pointer" [attr.modelURL]="value"
      (click)="$event.stopPropagation();getParts(assemblyLibrary)">
    <i class="fa fa-cube"></i>
</span>

<child-component></child-component>

很显然，我已将子组件导入到父组件中:

Obviously, I have imported the child component into the parent one:

import { SharedModule } from '../../shared'; //child declaration is inside here

在父组件中，我正在实现以下代码:

in the parent component, I am implementing the following code:

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

@Component({
    selector: 'parent-component',
    templateUrl: './parent-component.html',
    changeDetection: ChangeDetectionStrategy.OnPush
})
export class ParentComponent implements OnChanges, OnInit {
    ...

    @ViewChild('ChildComponent') childComponent;

    openDialog(filesToLoad) {
        this.childComponent.openDialog(filesToLoad);
    }

    getParts(value) {
        this.filesToLoad = [];

        ... code to populate files to load

        this.openDialog(this.filesToLoad);
    }}
}

当我通过单击HTML中声明的来调用getParts(value)时，出现以下错误:

When I call the getParts(value) by clicking on the declared in my HTML I get the following error:

VM21157:55例外:无法读取未定义的属性'openDialog'

VM21157:55 EXCEPTION: Cannot read property 'openDialog' of undefined

许多用户建议的这种方法有什么问题?

what is wrong with this approach suggested by many users?

推荐答案

父html应该类似于:

Parent html should be like:

<child-component #childComponent></child-component>

然后您可以使用@ViewChild

export class ParentComponent implements OnChanges, OnInit {
    ...

    @ViewChild('childComponent') childComponent;

现在，由于模板中没有#ChildComponent选择器，因此@ViewChild('ChildComponent') childComponent;不会选择任何内容.

Right now your @ViewChild('ChildComponent') childComponent; selects nothing since you don't have a #ChildComponent selector in your template.

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