Interface that a class can implement to be a guard deciding if a Route can be matched. If all guards return true, navigation continues and the Router will use the Route during activation. If any guard returns false, the Route is skipped for matching and other Route configurations are processed instead.

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

Description

The following example implements a CanMatch function that decides whether the current user has permission to access the users page.

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

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

  canMatch(route: Route, segments: UrlSegment[]): Observable<boolean>|Promise<boolean>|boolean {
    return this.permissions.canAccess(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: () => import('./team').then(mod => mod.TeamModule),
        canMatch: [CanMatchTeamSection]
      },
      {
        path: '**',
        component: NotFoundComponent
      }
    ])
  ],
  providers: [CanMatchTeamSection, UserToken, Permissions]
})
class AppModule {}

If the CanMatchTeamSection were to return false, the router would continue navigating to the team/:id URL, but would load the NotFoundComponent because the Route for 'team/:id' could not be used for a URL match but the catch-all ** Route did instead.

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

@NgModule({
  imports: [
    RouterModule.forRoot([
      {
        path: 'team/:id',
        component: TeamComponent,
        loadChildren: () => import('./team').then(mod => mod.TeamModule),
        canMatch: [(route: Route, segments: UrlSegment[]) => true]
      },
      {
        path: '**',
        component: NotFoundComponent
      }
    ])
  ],
})
class AppModule {}

Methods