CanLoad

Interface that a class can implement to be a guard deciding if children can be loaded. If all guards return true, navigation continues. If any guard returns false, navigation is cancelled. If any guard returns a UrlTree, current navigation is cancelled and a new navigation starts to the UrlTree returned from the guard.

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interface CanLoad {
  canLoad(route: Route, segments: UrlSegment[]): Observable<boolean | UrlTree> | Promise<boolean | UrlTree> | boolean | UrlTree
}

Description

The following example implements a CanLoad function that decides whether the current user has permission to load requested child routes.

class UserToken {}
class Permissions {
  canLoadChildren(user: UserToken, id: string, segments: UrlSegment[]): boolean {
    return true;
  }
}

@Injectable()
class CanLoadTeamSection implements CanLoad {
  constructor(private permissions: Permissions, private currentUser: UserToken) {}

  canLoad(route: Route, segments: UrlSegment[]): Observable<boolean>|Promise<boolean>|boolean {
    return this.permissions.canLoadChildren(this.currentUser, route, segments);
  }
}

Here, the defined guard function is provided as part of the Route object in the router configuration:

@NgModule({
  imports: [
    RouterModule.forRoot([
      {
        path: 'team/:id',
        component: TeamComponent,
        loadChildren: 'team.js',
        canLoad: [CanLoadTeamSection]
      }
    ])
  ],
  providers: [CanLoadTeamSection, UserToken, Permissions]
})
class AppModule {}

You can alternatively provide an in-line function with the canLoad signature:

@NgModule({
  imports: [
    RouterModule.forRoot([
      {
        path: 'team/:id',
        component: TeamComponent,
        loadChildren: 'team.js',
        canLoad: ['canLoadTeamSection']
      }
    ])
  ],
  providers: [
    {
      provide: 'canLoadTeamSection',
      useValue: (route: Route, segments: UrlSegment[]) => true
    }
  ]
})
class AppModule {}

Methods

canLoad()
canLoad(route: Route, segments: UrlSegment[]): Observable<boolean | UrlTree> | Promise<boolean | UrlTree> | boolean | UrlTree Parameters route Route segments UrlSegment[] Returns Observable<boolean | UrlTree> | Promise<boolean | UrlTree> | boolean | UrlTree