如何在 TabView (PrimeNG) 中延迟加载 Angular 2 个组件？

Question

这是我的 app.component.ts:

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

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

}

这是我的 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>

我的三个组件（home、tree和config）在加载tabView的时候同时加载了。但是，我希望在选择选项卡时加载组件。怎么做？

P.S.: 如果有帮助，TabView 有一个 onChange 事件。

Answer 1

你可以使用angular2路由中使用的SystemJsNgModuleLoader

Live Plunker

首先你可以编写组件来加载模块：

@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();
  }
}

然后在你的组件中使用它：

@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;
  }
}

另见

Answer 2

经过大量研究，我可以使用 router 解决问题。现在申请速度真快。

app.component.ts:

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

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

    constructor(
        private router: Router) {
    }

    handleChange(e) {
        let index = e.index;
        let link;
        switch (index) {
            case 0:
                link = ['/home'];
                break;
            case 1:
                link = ['/hierarquia'];
                break;
            case 2:
                link = ['/config'];
                break;
        }
        this.router.navigate(link);
    }
}

app.component.html:

<div>
    <p-tabView (onChange)="handleChange($event)">
        <p-tabPanel header="Home" leftIcon="fa-bar-chart-o"></p-tabPanel>
        <p-tabPanel header="Hierarquia" leftIcon="fa-sitemap"></p-tabPanel>
        <p-tabPanel header="Configurações" leftIcon="fa-cog"></p-tabPanel>
    </p-tabView>
</div>

<router-outlet></router-outlet>

app.route.ts:

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';

import { AppHome } from './app.home';
import { AppTree } from './app.tree';
import { AppConfig } from './app.config';

const routes: Routes = [
    {
        path: 'home',
        component: AppHome
    },
    {
        path: 'hierarquia',
        component: AppTree
    },
    {
        path: 'config',
        component: AppConfig
    },
    {
        path: '',
        redirectTo: '/home',
        pathMatch: 'full'
    },
];

@NgModule({
    imports: [RouterModule.forRoot(routes)],
    exports: [RouterModule]
})
export class AppRoutingModule { }

export const routedComponents = [AppHome, AppTree, AppConfig];

app.module.ts:

import { NgModule } from '@angular/core';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { HttpModule } from '@angular/http';
import { BrowserModule } from '@angular/platform-browser';
import 'rxjs/add/operator/toPromise';

import { AppConfig } from './app.config';
import { AppHeader } from './app.header';
import { AppHome } from './app.home';
import { AppTree } from './app.tree';
import { AppComponent } from './app.component';

import { AppRoutingModule, routedComponents } from './app.route';

import { InputTextModule, DataTableModule, ButtonModule, DialogModule, TabViewModule, ChartModule, TreeModule, GrowlModule, InputSwitchModule, BlockUIModule, InputMaskModule, DropdownModule } from 'primeng/primeng';

@NgModule({
    imports: [BrowserModule, FormsModule, ReactiveFormsModule, HttpModule, AppRoutingModule, InputTextModule, DataTableModule, ButtonModule, DialogModule, TabViewModule, ChartModule, TreeModule, GrowlModule, InputSwitchModule, BlockUIModule, InputMaskModule, DropdownModule],
    declarations: [AppHeader, AppComponent, AppHome, AppTree, AppConfig, routedComponents],
    bootstrap: [AppHeader, AppComponent]
})
export class AppModule { }

感谢上帝！ =]

Answer 3

Primeng 选项卡视图有一个 "lazy" 属性，默认为 "false"。您可以设置如下

<p-tabView [lazy]="true">

Answer 4

我试过 lazy 属性，但不起作用。使用 router 和 ModuleLoader 很棒，但有点复杂。如果你想让你的应用程序不要太复杂，最简单的解决方案是使用 NgIf 来渲染选项卡。

<p-tabView (onChange)="handleChange($event)">
   <p-tabPanel header="Home" leftIcon="fa-bar-chart-o">
      <home-app *ngIf="activeTab === 0"></home-app>
   </p-tabPanel>
   <p-tabPanel header="Hierarquia" leftIcon="fa-sitemap">
      <tree-app *ngIf="activeTab === 1"></tree-app>
   </p-tabPanel>
   <p-tabPanel header="Configurações" leftIcon="fa-cog">
      <config-app *ngIf="activeTab === 2"></config-app>
   </p-tabPanel>
</p-tabView>

并定义一个标志来呈现选定的选项卡。

handleChange(e) {
   this.activeTab = e.index;
}

Answer 5

这个问题很老了，不知道有没有用，不过我也是无意中发现了这个问题，PrimeNG文档里的答案是对的：

Lazy loading helps initial load performance by only initializing the active tab, inactive tabs are not initialized until they get selected. A lazy loaded tabpanel contents are cached by default so that upon reselection, they are not created again. You may use cache property on TabPanel to configure this behavior. A TabPanel is specified as lazy when there is a ngTemplate with pTemplate="content" in it.

来自 https://www.primefaces.org/primeng/#/tabview

尽管这仅出现在 V7 文档中，但此行为 在我使用的 V5.2 中同样有效。

我可以通过检查 Chrome DevTools 中的 "network" 选项卡来验证它，每个选项卡面板都按预期单独加载。不过缓存属性好像不存在，所以会一直缓存

那么对于作者来说，他可以做到：

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

如何在 TabView (PrimeNG) 中延迟加载 Angular 2 个组件？

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

lazy-loading

tabview

typescript

primeng

angular