CanDeactivate interface

This is the documentation for Angular 6.
You can switch to the latest version Angular 7.

Interface that a class can implement to be a guard deciding if a route can be deactivated.

interface CanDeactivate<T> {
  canDeactivate(component: T, currentRoute: ActivatedRouteSnapshot, currentState: RouterStateSnapshot, nextState?: RouterStateSnapshot): Observable<boolean> | Promise<boolean> | boolean
}

Example

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

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

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

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

You can alternatively provide a function with the canDeactivate signature:

@NgModule({
  imports: [
    RouterModule.forRoot([
      {
        path: 'team/:id',
        component: TeamCmp,
        canDeactivate: ['canDeactivateTeam']
      }
    ])
  ],
  providers: [
    {
      provide: 'canDeactivateTeam',
      useValue: (component: TeamComponent, currentRoute: ActivatedRouteSnapshot, currentState:
RouterStateSnapshot, nextState: RouterStateSnapshot) => true
    }
  ]
})
class AppModule {}