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Angular: How to route different modules on the same path depending on service

Imagine a service ABService with a method isAResponsible: () => boolean and two modules: AModule and BModule.

The question is: Is it possible to switch between AModule and BModule depending on what isAResponsible returns? And how do we 'reroute' and rerender if the value of isAResponsible changes? ABService may have several dependencies to other services so it would be preferable to make use of the DI system somehow.

Example: If the route of interest is /aorb and ABService.isAResponsible returns true, than we would like to route AModule. If ABService.isAResponsible returns false however we want BModule to manage further routing. Note that everything should happen on a shared route.

I tried it with guards and canActivate/canLoad but didn't succeed:

app.module.ts

import { NgModule } from '@angular/core';
import { RouterModule } from '@angular/router';
import { BrowserModule } from '@angular/platform-browser';

import { AppComponent } from './app.component';
import { AorBActivateGuard } from './aorb-activate.guard';
import { ABService } from './ab.service';

@NgModule({
  imports: [
    BrowserModule,
    RouterModule.forRoot([
      {
        path: 'aorb',
        canActivate: [AorBActivateGuard],
        loadChildren: () => import('./a/a.module').then((m) => m.AModule),
      },
      {
        path: 'aorb',
        loadChildren: () => import('./b/b.module').then((m) => m.BModule),
      },
    ]),
  ],
  providers: [AorBActivateGuard, ABService],
  declarations: [AppComponent],
  bootstrap: [AppComponent],
})
export class AppModule {}

ab.service.ts

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

@Injectable()
export class ABService {
  private aIsResponsible = true;

  constructor() {}

  switch() {
    this.aIsResponsible = !this.aIsResponsible;
  }

  isAResponsible() {
    return this.aIsResponsible;
  }
}

aorb-activate.guard.ts

import { Injectable } from '@angular/core';
import {
  CanActivate,
  ActivatedRouteSnapshot,
  RouterStateSnapshot,
} from '@angular/router';
import { Observable } from 'rxjs';
import { ABService } from './ab.service';

@Injectable()
export class AorBActivateGuard implements CanActivate {
  constructor(private abService: ABService) {}

  canActivate(
    next: ActivatedRouteSnapshot,
    state: RouterStateSnapshot
  ): Observable<boolean> | Promise<boolean> | boolean {
    return this.abService.isAResponsible();
  }
}

over 4 years ago · Santiago Trujillo

2 answers

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You can you try this instead, I have just checked locally it works, just think it in a different way and you have your solution :)

import { NgModule } from '@angular/core';
import { RouterModule } from '@angular/router';
import { BrowserModule } from '@angular/platform-browser';

import { AppComponent } from './app.component';
import { AorBActivateGuard } from './aorb-activate.guard';
import { ABService } from './ab.service';

@NgModule({
  imports: [
    BrowserModule,
    RouterModule.forRoot([
      {
        path: 'aorb',
        loadChildren: () => {
          if ((new ABService()).isAResponsible()){
            return import('./a/a.module').then((m) => m.AModule)
          } else {
            return import('./b/b.module').then((m) => m.BModule)
          }
        },
      },
    ]),
  ],
  providers: [AorBActivateGuard, ABService],
  declarations: [AppComponent],
  bootstrap: [AppComponent],
})
export class AppModule {}

over 4 years ago · Santiago Trujillo Report

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Accepted Answer · 2022-03-03T18:27:14.212Z

One can inject ABService in AppModule and listen for changes from ABService. Every time a change occurs we then can reconfigure (= switch modules) the router and let it navigate the same route. In this way we always have the responsible module loaded.

[...]
@NgModule({
  imports: [
    BrowserModule,
    RouterModule.forRoot([], {
      initialNavigation: 'disabled',
    }),
  ],
  providers: [ABService, BooleanStorageService],
  declarations: [AppComponent],
  bootstrap: [AppComponent],
})
export class AppModule {
  constructor(private router: Router, private abService: ABService) {
    abService.onABChange.subscribe(this.resetRouterConfig(true).bind(this));
    this.resetRouterConfig(false)();
    this.router.initialNavigation();
  }

  reloadCurrentRoute() {
    const currentUrl = this.router.url;
    this.router.navigateByUrl('/', { skipLocationChange: true }).then(() => {
      this.router.navigate([currentUrl]);
    });
  }

  resetRouterConfig(refresh: boolean) {
    return () => {
      const constructedConfig = [
        {
          path: '',
          pathMatch: 'full',
          redirectTo: 'aorb',
        },
        {
          path: 'aorb',
          loadChildren: () => {
            if (this.abService.isAResponsible()) {
              return import('./a/a.module').then((m) => m.AModule);
            } else {
              return import('./b/b.module').then((m) => m.BModule);
            }
          },
        },
      ];

      this.router.resetConfig(constructedConfig);

      if (refresh) this.reloadCurrentRoute();
    };
  }
}

You can find a working example here.

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