CODEWITHSUNDEEP
angularrxjsangular2-routingangular6
liad drori
liad drori

Reputation: 13

Route guard with auth.service

I'm trying to create a route guard that keeps some lazy-loaded module safe, I have a auth service with BehaviorSubject that holds current user and JWT token

When I call the guard it first gets the default value of the current user and only on secend try it allow the user to get to the route.

auth.service.ts:

import { Injectable } from '@angular/core';
import { HttpClient, HttpErrorResponse, HttpResponse, HttpHeaders } from '@angular/common/http';
import { Observable, BehaviorSubject } from 'rxjs';
import { map, skip, takeLast, last } from 'rxjs/operators';

import { User } from '../shared/user';
import { environment } from '../../environments/environment';


@Injectable()
export class AuthService {
  private loginUserToken: BehaviorSubject<string>;
  private currentUser: BehaviorSubject<User>;
  constructor(private http: HttpClient) {
    // service init
    this.loginUserToken = new BehaviorSubject(undefined);
    this.currentUser = new BehaviorSubject(undefined);
    this.loginUserToken.next(this.getTokenFromLocalStorege());
    if (this.loginUserToken.value != null) {
      this.getUserFromToken();
    }
  }
  /**
   * getLoginUser
   */
  public getLoginUserAsObservable() {
    return this.currentUser.asObservable();
  }
  public getLoginUserTokenAsObservable() {
    return this.loginUserToken.asObservable();
  }
  public async login(user: User): Promise<any> {
    // tslint:disable-next-line:no-shadowed-variable
    return new Promise<any>(async (resolve: any, reject: any) => {
      try {
        const result: any = await this.http.post(`${environment.server}/api/auth/login`, user).toPromise();
        if (result.massageCode === 1) {
          reject('bedUsername');
        } else if (result.massageCode === 2) {
          reject('bed password');
        } else {
          this.loginUserToken.next(result.token);
          this.getUserFromToken();
          this.saveTokenToLocalStorege(result.token);
          resolve();
        }
      } catch (error) {
        reject('error');
      }
    });
  }
  public getUserFromToken(): void {
    const headers = new HttpHeaders({
      'x-access-token': this.loginUserToken.value
    });
    this.http.get(`${environment.server}/api/auth/userFromToken`, { headers }).toPromise()
      .then((data: User) => {
        this.currentUser.next(data);
      })
      .catch((error) => {
        console.log(error);
      });
  }
  public isLogin(): Promise<boolean> {
    return new Promise((resolve, reject) => {
      this.currentUser.asObservable()
      .subscribe((data) => {
        if (data) {
          resolve(true);
        } else {
          resolve(false);
        }
      }).unsubscribe();
    });
  }
  public saveTokenToLocalStorege(token: string): void {
    localStorage.setItem('chanToken', token);
  }
  public getTokenFromLocalStorege(): string {
    return localStorage.getItem('chanToken');
  }
  public removeTokenFromLocalStrege(): void {
    localStorage.removeItem('chanToken');
  }
}

auth.guaed.ts:

import { Injectable } from '@angular/core';
import { CanActivate, CanLoad, ActivatedRouteSnapshot, RouterStateSnapshot, Router } from '@angular/router';
import { Observable } from 'rxjs';
import { AuthService } from '../auth.service';
import { Route } from '@angular/compiler/src/core';
import { last, map } from 'rxjs/operators';
@Injectable()
export class AuthGuard implements CanLoad {

  constructor(private authSerivce: AuthService, private router: Router) { }

  canLoad(route: Route): boolean | Observable<boolean> | Promise<boolean> {
    console.log('use gruad');
    return this.authSerivce.isLogin();
  }
}

Upvotes: 0

Views: 1332

Answers (1)

SplitterAlex
SplitterAlex

Reputation: 2823

That's because how a BehaviourSubject works. When you Subscribe to a BehaviourSubject it immediately returns the last value. That's why a BehaviourSubject needs a default value.

In your case as soon the AuthGuard gets activated it will call your method isLogin which subscribes to currentUser and it will return undefined (Depending on the sequence of javascript execution). Basically your AuthGuard will not wait for your function getUserFromToken() to finish.

You can easily solve this solution when you use ReplaySubject instead of BehaviourSubject.

private currentUser: ReplaySubject<User> = new ReplaySubject(1)

Initialize ReplaySubject with the value of 1 and it will cache your current user, but will not fire when there no user exist.

For now on your Authguard will wait for a valid currentUser value and will not fire when currentUser is undefined

Upvotes: 3

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