CanDeactivate

Interface that a class can implement to be a guard deciding if a route can be deactivated. 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 begins to the UrlTree returned from the guard.

The following example implements a CanDeactivate function that checks whether the current user has permission to deactivate the requested route.

class UserToken {}
class Permissions {
  canDeactivate(user: UserToken, id: string): boolean {
    return true;
  }
}

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

@Injectable()
class CanDeactivateTeam implements CanDeactivate<TeamComponent> {
  constructor(private permissions: Permissions, private currentUser: UserToken) {}

  canDeactivate(
    component: TeamComponent,
    currentRoute: ActivatedRouteSnapshot,
    currentState: RouterStateSnapshot,
    nextState: RouterStateSnapshot
  ): MaybeAsync<GuardResult> {
    return this.permissions.canDeactivate(this.currentUser, route.params.id);
  }
}

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