Angular 2：在创建组件时动态插入捕获元素（动态）

Question

我的目标是创建一个子组件并插入到父组件模板中。有一些例子可以做到这一点。 但是，我在父组件中动态创建父组件模板（DOM 元素），而显示的大多数示例都是使用捕获元素静态创建模板。

这是代码

app.component

import {Component, ViewChild, ViewContainerRef, ComponentFactoryResolver} from '@angular/core';
import {NewChildComponent} from "./newChild.component";

@Component({
 selector: 'app-main',
 templateUrl: 'app.component.html'
})
export class AppComponent {

 @ViewChild('captureElement', {read: ViewContainerRef})
 captureElement: ViewContainerRef;

 constructor (private componentFactoryResolver: ComponentFactoryResolver) {
 var childComponent = this.componentFactoryResolver.resolveComponentFactory(NewChildComponent); 

 var myArea = document.getElementById('myArea');
 var myRow = document.createElement("div");
 myArea.appendChild(myRow);

 //I want to add the capture element #myCapture as a child of myRow
 //Add something like this <div #captureElement></div> programmatically through JS/TS
 // How can I do this?

 // I then create the component
  this.parent.createComponent(NewChildComponent);

 }

app.component.html

<div id="myArea">
  <!-- Static way of doing it -->
  <!--<div #captureElement></div>-->      
</div>

我不想在#captureElement 中静态定义插入子组件的位置，而是想在父组件中动态创建它并使其成为子组件。

这是我在问这个问题之前提到的问题列表

• Angular2: Insert a dynamic component as child of a container in the DOM
• How to place a dynamic component in a container
• Angular 2 dynamic tabs with user-click chosen components

尝试了几件事

1. 试图用#captureElement 创建一个div 元素作为 以编程方式设置属性，但这不起作用。
2. 尝试以编程方式创建一个随机元素并使用ViewContainerRef 找到它。那也不行。

Answer 1

我们无法创建ViewContainerRef，因为ViewContainerRef 仅存在于视图中。

在 2.3.0 中，引入了 attachView，它允许您将更改检测附加到 ApplicationRef。您可以创建一些类来封装您的逻辑，例如：

export class HtmlContainer {
   private attached: boolean = false;

   private disposeFn: () => void;

   constructor(
    private hostElement: Element,
    private appRef: ApplicationRef,
    private componentFactoryResolver: ComponentFactoryResolver, 
    private injector: Injector) {
  }

  attach(component: Type<any>) : ComponentRef<any> {
    if(this.attached) {
      throw new Error('component has already been attached')
    }

    this.attached = true;
    const childComponentFactory = this.componentFactoryResolver.resolveComponentFactory(component);

    let componentRef = childComponentFactory.create(this.injector);

    this.appRef.attachView(componentRef.hostView);
    this.disposeFn = () => {
        this.appRef.detachView(componentRef.hostView);
        componentRef.destroy();
    };

    this.hostElement.appendChild((componentRef.hostView as EmbeddedViewRef<any>).rootNodes[0]);

    return componentRef;
  }

  dispose() {
    if(this.attached) {
      this.disposeFn();
    }
  }
}

这个类只是帮助

1) 解析你的动态组件

this.componentFactoryResolver.resolveComponentFactory(component);

2) 然后调用compFactory.create编译组件

3) 之后通过调用上述appRef.attachView 注册其changeDetector（componentRef.hostView 扩展ChangeDetectorRef）（否则更改检测将不适用于您的组件）

4) 最后将组件的 rootNode 附加到宿主元素

this.hostElement.appendChild((componentRef.hostView as EmbeddedViewRef<any>).rootNodes[0]);

你可以按如下方式使用它：

@Component({
  selector: 'my-app',
  template: `<div id="myArea"></div> `,
  entryComponents: [NewChildComponent]
})
export class AppComponent {
  containers: HtmlContainer[] = [];

  constructor(
    private appRef: ApplicationRef,
    private componentFactoryResolver: ComponentFactoryResolver, 
    private injector: Injector) {
  }

  ngOnInit() {
    var myArea = document.getElementById('myArea');
    var myRow = document.createElement("div");
    myArea.appendChild(myRow);

    this.addComponentToRow(NewChildComponent, myRow, 'test1');
    this.addComponentToRow(NewChildComponent, myRow, 'test2');
  }

  addComponentToRow(component: Type<any>, row: HTMLElement, param: string) {
    let container = new HtmlContainer(row, this.appRef, this.componentFactoryResolver, this.injector);
    let componentRef = container.attach(component);
    componentRef.instance.param1 = param;

    this.containers.push(container);
  }

  ngOnDestroy() {
    this.containers.forEach(container => container.dispose());
  }
}

Plunker Example

另见

• Angular2 - Component into dynamicaly created element
• Angular2 Dynamic Component Injection in Root
• https://github.com/angular/material2/blob/2.0.0-beta.1/src/lib/core/portal/dom-portal-host.ts#L30-L86（您可以在此处找到 angular