Loading a Component conditionally using Angular 2 Routes: A guide to asynchronous loading

If I want to dynamically attach a component to a route based on a condition asynchronously.

In the following instance, which functions but is asynchronous, it loads either one component or another depending on the user's role:

import { UserDashboardComponent } from './user-dashboard.component'
import { AdminDashboardComponent } from './admin-dashboard.component'

const role = 'admin' // Just an example
const comp = role === 'admin' ? AdminDashboardComponent : UserDashboardComponent

const routes: Routes = [
  { path: '', component: comp },
]

However, if we need to fetch the role from an API, making it asynchronous, what would be the procedure to achieve that?

Answer №1

If you want to streamline the process, consider creating a generic module called 'GenericModule' that houses both components in the declarations array:

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { UserDashboardComponent }  from './user-dashboard.component'
import { AdminDashboardComponent } from './admin-dashboard.component    

@NgModule({
  imports: [ BrowserModule ],
  declarations: [ UserDashboardComponent,AdminDashboardComponent ]
})
export class GenericModule { }

This setup allows you to have all the necessary modules in one place for easy loading.

To load these components asynchronously using the compiler, follow these steps within your component:

import {GenericModule} from './generic.module';
import { Component, Input, ViewContainerRef, Compiler, NgModule, ModuleWithComponentFactories, OnInit, ViewChild} from '@angular/core';
@Component({
  selector: 'generic',
  template: '<div #target></div>'
})
export class App implements AfterViewInit {
  @ViewChild('target', {read: ViewContainerRef}) target: ViewContainerRef;

  constructor(private compiler: Compiler) {}

  ngAfterViewInit() {
    this.createComponent('<u>Example template...</u>');
  }

  private createComponent(template: string, role:string) {
    @Component({template: template});
    const mod = this.compiler.compileModuleAndAllComponentsSync(GenericModule);
    const factory = mod.componentFactories.find((comp) =>
    //you can add your comparison condition here to load the component
    //for eg. comp.selector===role where role='admin'
    );
    const component = this.target.createComponent(factory);
  }
}

By following these guidelines, you can optimize the loading process and enhance efficiency.

Answer №2

Lazy loading at the module level is a feature supported by Angular 2. Instead of components, feature modules are loaded asynchronously. To implement this, you can turn your component into a feature module. Learn more about lazy loading in Angular 2 here

Answer №3

One approach is to create a DashboardComponent, which serves as a higher-level component that can be accessed at the route /dashboards.

Within this parent component, you can dynamically load child components in its template based on certain asynchronous conditions.

This method allows you to utilize *ngIf within the parent component, keeping the child components templates clean and uncluttered.

Answer №4

In order to streamline your process and use a single route for both components, consider creating an additional component specifically for that route. This new component can then reference both existing components in its template, using ngIf statements as shown below:

<user-dashboard *ngIf="role==='user'"></user-dashboard>
<admin-dashboard *ngIf="role==='admin'"></admin-dashboard>

Answer №5

My recommendation is to utilize programmatic navigation by using the router's navigate method. Make sure to include all potential routes in the router file, and then within your component, call router.navigate() as needed for each specific scenario.

Answer №6

If you're looking for a solid solution, consider using an auth-guard. You can implement interfaces such as CanActivate/CanLoad and specify your conditions within that class.

When the condition is met, routes will be activated accordingly.

For example:

import { Injectable }       from '@angular/core';
import {
  CanActivate,
  ActivatedRouteSnapshot,
  RouterStateSnapshot
}                           from '@angular/router';
import { Observable } from 'rxjs/Observable';
import { Router } from '@angular/router';

@Injectable()
export class AuthorizationGuard implements CanActivate {
  constructor() {}

  canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): 
       Observable<boolean> {
    let url: string = state.url;
    return this.canbeLoaded(url);
  }

  canbeLoaded(url: string): Observable<boolean> {
    return Observable.of(true);  //put your condition here
  }
}

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