Angular 6 HttpInterceptor interface fail on production

Question

I'm using HttpInterceptor interface to add authorisation header on http petitions,

@Injectable()
export class AuthInterceptor implements HttpInterceptor {

    constructor(
        private localStorage: LocalStorageService,
        private sessionStorage: SessionStorageService
    ) {
    }

    intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        if (!request || !request.url || (/^http/.test(request.url) && !(SERVER_API_URL && request.url.startsWith(SERVER_API_URL)))) {
            return next.handle(request);
        }

        const token = this.localStorage.retrieve('authenticationToken') || this.sessionStorage.retrieve('authenticationToken');
        if (!!token) {
            request = request.clone({
                setHeaders: {
                    Authorization: 'Bearer ' + token
                }
            });
        }
        return next.handle(request);
    }

}

my app module

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
      BrowserModule,
      AppRoutingModule,
      HttpClientModule,
      VistaModule,
      LayoutModule
  ],
  providers: [
    {
      provide: HTTP_INTERCEPTORS,
      useClass: AuthInterceptor,
      multi: true
    }
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

Locally it works perfectly but it fails when generates prod dist and uploads on server. Any petition obtains headers: Object, status: 401, statusText: "Unauthorized"

Can you help me?

Answer 1

Declare your Interceptor to be provided in root:

@Injectable({
    providedIn: 'root'
})

instead of using just:

@Injectable()

It means that your interceptor will be available in all your application, this in the case you have another module for product which could be the problem.

Check more details on: Angular Providers