


A brief discussion on the implementation method of dynamic loading of components in angular9
Load components according to conditions to achieve flexible switching of components and reduce the use of a large number of ngIf. It is also a relatively common operation in angular. In this article, we will share with you the dynamic use of angular components. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.
Creation of directives
Before adding a component, you must first define an anchor point to tell Angular where to insert the component. place.
Under src/dynamic-banner/ad.directive.ts
import { Directive, ViewContainerRef } from '@angular/core'; @Directive({ selector: '[ad-host]', }) export class AdDirective { constructor(public viewContainerRef: ViewContainerRef) { } }
AdDirective injects ViewContainerRef to obtain access to the container view. This container is the host of the dynamically added components.
In the @Directive decorator, pay attention to the name of the selector: ad-host, which is the directive you will apply to the element.
Related recommendations: "angular tutorial"
Core code of dynamic components
HTML loaded by dynamic components
src/dynamic-banner/ad-banner.component.html
<div> <h3 id="Advertisements">Advertisements</h3> <ng-template></ng-template> </div>
ts of dynamic components
src/dynamic-banner /ad-banner.component.ts
import { Component, Input, OnInit, ViewChild, ComponentFactoryResolver, OnDestroy, SimpleChanges } from '@angular/core'; import { AdDirective } from './ad.directive'; import { AdItem } from './ad-item'; import { AdComponent } from './ad.component'; import { componentMap } from './component/utils'; @Component({ selector: 'app-ad-banner', templateUrl: './ad-banner.component.html', // styleUrls: ['./ad-banner.component.css'] }) export class AdBannerComponent implements OnInit { @Input() type: string = 'ad1' // 传入的key,确定加载那个组件 @Input() data: any = {} // 传入组件的数据 @ViewChild(AdDirective, {static: true}) adHost: AdDirective; // 动态组件的指令 constructor(private componentFactoryResolver: ComponentFactoryResolver) { } ngOnInit() { this.loadComponent(); } ngOnChanges(changes: SimpleChanges): void { if (changes['type']) this.loadComponent() } loadComponent() { // adItem 要加载的组件类,以及绑定到该组件上的任意数据 const adItem = new AdItem(componentMap[this.type], this.data) const componentFactory = this.componentFactoryResolver.resolveComponentFactory(adItem.component); const viewContainerRef = this.adHost.viewContainerRef; viewContainerRef.clear(); const componentRef = viewContainerRef.createComponent(componentFactory); (<adcomponent>componentRef.instance).data = adItem.data; } }</adcomponent>
ad-item.ts
src/dynamic-banner/ad-item.ts
import { Type } from '@angular/core'; export class AdItem { constructor(public component: Type<any>, public data: any) {} }</any>
ad.component.ts
src/dynamic-banner/ad.component.ts
import { Type } from '@angular/core'; export interface AdComponent { data: any; }
Unified component registration
src/dynamic-banner/share.module.ts
import { NgModule } from '@angular/core'; import { CommonModule } from '@angular/common'; import { componets } from './component/utils'; import { AdDirective } from './ad.directive'; import { AdBannerComponent } from './ad-banner.component'; @NgModule({ imports: [ CommonModule ], exports:[ [...componets], AdDirective, AdBannerComponent, ], declarations: [ [...componets], AdDirective, AdBannerComponent, ], entryComponents: [ [...componets] ] }) export class ShareModule { }
Component mapping
src/dynamic-banner/component/utils.ts
import { HeroProfileComponent } from "./hero-profile.component"; import { HeroJobAdComponent } from './hero-job-ad.component'; const componentMap = { ad1: HeroProfileComponent, ad2: HeroJobAdComponent } const componets = [ HeroProfileComponent, HeroJobAdComponent ] export {componets, componentMap}
Rendering
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