Angular 5 HttpClient Interceptor JWT refresh token unable to Catch 401 and Retry my request

Question

I am trying to implement a catch for 401 responses and tried obtaining a refresh token based on Angular 4 Interceptor retry requests after token refresh. I was trying to implement the same thing, but I never was able to Retry that request, and I am really not sure if that is the best approach to apply the refresh token strategy. Here is my code:

@Injectable()
export class AuthInterceptorService implements HttpInterceptor {
 public authService;
 refreshTokenInProgress = false;
 tokenRefreshedSource = new Subject();
 tokenRefreshed$ = this.tokenRefreshedSource.asObservable();
 constructor(private router: Router, private injector: Injector) { }
 authenticateRequest(req: HttpRequest<any>) {
 const token = this.authService.getToken();
 if (token != null) {
 return req.clone({
 headers: req.headers.set('Authorization', `Bearer ${token.access_token}`)
 });
 }
 else {
 return null;
 }
 }
 refreshToken() {
 if (this.refreshTokenInProgress) {
 return new Observable(observer => {
 this.tokenRefreshed$.subscribe(() => {
 observer.next();
 observer.complete();
 });
 });
 } else {
 this.refreshTokenInProgress = true;

 return this.authService.refreshToken()
 .do(() => {
 this.refreshTokenInProgress = false;
 this.tokenRefreshedSource.next();
 }).catch(
 (error) => {
 console.log(error);
 }
 );
 }
 }
 intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
 this.authService = this.injector.get(AuthenticationService);
 request = this.authenticateRequest(request);
 return next.handle(request).do((event: HttpEvent<any>) => {
 if (event instanceof HttpResponse) {
 // do stuff with response if you want
 }
 }, (err: any) => {
 if (err instanceof HttpErrorResponse) {
 if (err.status === 401) {
 return this.refreshToken()
 .switchMap(() => {
 request = this.authenticateRequest(request);
 console.log('*Repeating httpRequest*', request);
 return next.handle(request);
 })
 .catch(() => {
 return Observable.empty();
 });
 }
 }
 });
 }
}

The issue is that SwitchMap is never reached in...

if (err.status === 401) {
 return this.refreshToken()
 .switchMap(() => {

and the do operator as well...

return this.authService.refreshToken()
 .do(() => {

so that took me to my authService refreshToken method...

refreshToken() {
 let refreshToken = this.getToken();

 refreshToken.grant_type = 'refresh_token';
 refreshToken.clientId = environment.appSettings.clientId;
 return this.apiHelper.httpPost(url, refreshToken, null)
 .map
 (
 response => {
 this.setToken(response.data, refreshToken.email);
 return this.getToken();
 }
 ).catch(error => {

 return Observable.throw('Please insert credentials');
 });
 }
 }

It returns a mapped observable, and I know it needs a subscription if I replaced the do in...

return this.authService.refreshToken()
 .do(() => {

With subscribe I'll break the observable chain I guess. I am lost and I've playing with this for a long time without a solution. :D

Answer 1

I'm glad that you like my solution. I'm going to put just the final solution here but if anybody wants to know the process that I fallowed go here: Refresh Token OAuth Authentication Angular 4+

Ok, First I created a Service to save the state of the refresh token request and Observable to know when the request is done.

This is my Service:

@Injectable()
export class RefreshTokenService {
  public processing: boolean = false;
  public storage: Subject<any> = new Subject<any>();

  public publish(value: any) {
    this.storage.next(value);
  }
}

I noticed that It was better if I have two Interceptors one to refresh the token and handle that and one to put the Authorization Header if exist.

This the Interceptor for Refresh the Token:

@Injectable()
  export class RefreshTokenInterceptor implements HttpInterceptor {

    constructor(private injector: Injector, private tokenService: RefreshTokenService) {
    }

    intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
      const auth = this.injector.get(OAuthService);
      if (!auth.hasAuthorization() && auth.hasAuthorizationRefresh() && !this.tokenService.processing && request.url !== AUTHORIZE_URL) {
        this.tokenService.processing = true;
        return auth.refreshToken().flatMap(
          (res: any) => {
            auth.saveTokens(res);
            this.tokenService.publish(res);
            this.tokenService.processing = false;
            return next.handle(request);
          }
        ).catch(() => {
          this.tokenService.publish({});
          this.tokenService.processing = false;
          return next.handle(request);
        });
      } else if (request.url === AUTHORIZE_URL) {
        return next.handle(request);
      }

      if (this.tokenService.processing) {
        return this.tokenService.storage.flatMap(
          () => {
            return next.handle(request);
          }
        );
      } else {
        return next.handle(request);
      }
    }
  }

So here I'm waiting to the refresh token to be available or fails and then I release the request that needs the Authorization Header.

This is the Interceptor to put the Authorization Header:

@Injectable()
  export class TokenInterceptor implements HttpInterceptor {
    constructor(private injector: Injector) {}

    intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
      const auth = this.injector.get(OAuthService);
      let req = request;
      if (auth.hasAuthorization()) {
        req = request.clone({
          headers: request.headers.set('Authorization', auth.getHeaderAuthorization())
        });
      }

      return next.handle(req).do(
        () => {},
        (error: any) => {
          if (error instanceof HttpErrorResponse) {
            if (error.status === 401) {
              auth.logOut();
            }
          }
        });
    }
  }

And my main module is something like this:

@NgModule({
  imports: [
    ...,
    HttpClientModule
  ],
  declarations: [
    ...
  ],
  providers: [
    ...
    OAuthService,
    AuthService,
    RefreshTokenService,
    {
      provide: HTTP_INTERCEPTORS,
      useClass: RefreshTokenInterceptor,
      multi: true
    },
    {
      provide: HTTP_INTERCEPTORS,
      useClass: TokenInterceptor,
      multi: true
    }
  ],
  bootstrap: [AppComponent]
})
export class AppModule {
}

Please any feedback will be welcome and if I'm doning something wrong tell me. I'm testing with Angular 4.4.6 but I don't know if it work on angular 5, I think should work.