相关疑难解决方法(0)

我有一个Angular 2服务:

import {Storage} from './storage';
import {Injectable} from 'angular2/core';
import {Subject}    from 'rxjs/Subject';

@Injectable()
export class SessionStorage extends Storage {
  private _isLoggedInSource = new Subject<boolean>();
  isLoggedIn = this._isLoggedInSource.asObservable();
  constructor() {
    super('session');
  }
  setIsLoggedIn(value: boolean) {
    this.setItem('_isLoggedIn', value, () => {
      this._isLoggedInSource.next(value);
    });
  }
}

一切都很好.但我有另一个不需要订阅的组件,它只需要在某个时间点获取isLoggedIn的当前值.我怎样才能做到这一点？

我发现使用Auth Guards的实现很少AuthGuard.在我的项目中,我曾经take(1)满足我的需求.它的工作方式是否相同？或者其中一个可能有优势.

import 'rxjs/add/operator/map';
import 'rxjs/add/operator/first';
import { Observable } from 'rxjs/Observable';

import { Injectable } from '@angular/core';
import { CanActivate, Router, ActivatedRouteSnapshot, RouterStateSnapshot } from '@angular/router';
import { AngularFire } from 'angularfire2';

@Injectable()
export class AuthGuard implements CanActivate {

    constructor(private angularFire: AngularFire, private router: Router) { }

    canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<boolean> | boolean {
        return this.angularFire.auth.map(
            (auth) =>  {
                if (auth) {
                    this.router.navigate(['/dashboard']);
                    return false;
                } else {
                    return true;
                }
            }
        ).first(); // …