How to lazy load Angular 2 components in a TabView (PrimeNG)?

Question

It is my app.component.ts:

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

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

}

And this is my app.component.html:

<p-tabView>
    <p-tabPanel header="Home" leftIcon="fa-bar-chart-o">
        <home-app></home-app>
    </p-tabPanel>
    <p-tabPanel header="Hierarquia" leftIcon="fa-sitemap">
        <tree-app></tree-app>
    </p-tabPanel>
    <p-tabPanel header="Configurações" leftIcon="fa-cog">
        <config-app></config-app>
    </p-tabPanel>
</p-tabView>

My three components (home, tree and config) are been loaded at the same time when the tabView is loaded. However, I would like that a component was loaded just when its tab was selected. How to do that?

P.S.: if it helps, TabView has an onChange event.

Answer 1

You can use SystemJsNgModuleLoader which is used in angular2 routing

Live Plunker

First you can write component which will load module:

@Component({
  selector: 'dynamic-container',
  template: `
    <template #container></template>
    <div *ngIf="!loaded" class="loader"></div>
  `,
  styles: [`
    .loader {
      position: relative;
      min-height: 100px;
    }

    .loader:after {
      content: 'Loading module. Please waiting...';
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
    }
  `]
})
export class DynamicContainerComponent implements OnDestroy {
  @ViewChild('container', { read: ViewContainerRef }) vcRef: ViewContainerRef;
  loaded: boolean;

  constructor(private moduleLoader: SystemJsNgModuleLoader) { }

  compRef: ComponentRef<any>;

  @Input() modulePath: string;
  @Input() moduleName: string;

  _inited: boolean
  set inited(val: boolean) {
    if(val) {
      this.loadComponent();
    }
    this._inited = val;
  };

  get inited() {
    return this._inited;
  }

  loadComponent() {
    this.moduleLoader.load(`${this.modulePath}#${this.moduleName}`)
      .then((moduleFactory: NgModuleFactory<any>) => {
        const vcRef = this.vcRef;
        const ngModuleRef = moduleFactory.create(vcRef.parentInjector);
        const comp = ngModuleRef.injector.get(LazyLoadConfig).component;
        const compFactory = ngModuleRef.componentFactoryResolver.resolveComponentFactory(comp);
        this.compRef = vcRef.createComponent(compFactory, 0, ngModuleRef.injector);

        this.loaded = true;
      });
  }

  ngOnDestroy() {
    this.compRef.destroy();
  }
}

And then use it in your component:

@Component({
  selector: 'my-app',
  template: `
    <h2 class="plunker-title">How to lazy load Angular 2 components in a TabView (PrimeNG)?</h2>
    <p-tabView (onChange)="handleChange($event)">
    <p-tabPanel header="Home" leftIcon="fa-bar-chart-o">
        <home-app></home-app>
    </p-tabPanel>
    <p-tabPanel header="Hierarquia" leftIcon="fa-sitemap">
        <dynamic-container modulePath="./src/modules/tree/tree.module" moduleName="TreeModule"></dynamic-container>
    </p-tabPanel>
    <p-tabPanel header="Configurações" leftIcon="fa-cog">
        <dynamic-container modulePath="./src/modules/config/config.module" moduleName="ConfigModule"></dynamic-container>
    </p-tabPanel>
</p-tabView>
  `
})
export class AppComponent {
  @ViewChildren(DynamicContainerComponent) dynamicContainers: QueryList<DynamicContainerComponent>;

  handleChange(e) {
    let dynamicContainer = this.dynamicContainers.toArray()[e.index - 1];
    if (!dynamicContainer || dynamicContainer.inited) return;

    // prevent fast clicking and double loading
    dynamicContainer.inited = true;
  }
}

See also

• How to manually lazy load a module?