Angular 4.3 - HTTP Interceptor - refresh JWT token

Question

I need to react (in interceptor class) on 403 Forbidden HTTP status (to obtain/refresh) JWT token and retry the request with fresh token.

In the code below, when ser

Answer 1

Just wanted to share what worked for me:

@Injectable()
export class AutoReLoginInterceptor implements HttpInterceptor {

    constructor() {
    }

    intercept(req: HttpRequest, next: HttpHandler): Observable> {
        // as we want to intercept the possible errors, instead of directly returning the request execution, we return an Observable to control EVERYTHING
        return new Observable>(subscriber => {

            // first try for the request
            next.handle(req)
                .subscribe((event: HttpEvent) => {
                        if (event instanceof HttpResponse) {
                            // the request went well and we have valid response
                            // give response to user and complete the subscription
                            subscriber.next(event);
                            subscriber.complete();
                        }
                    },
                    error => {
                        if (error instanceof HttpErrorResponse && error.status === 401) {
                            console.log('401 error, trying to re-login');

                            // try to re-log the user
                            this.reLogin().subscribe(authToken => {
                                // re-login successful -> create new headers with the new auth token
                                let newRequest = req.clone({
                                    headers: req.headers.set('Authorization', authToken)
                                });

                                // retry the request with the new token
                                next.handle(newRequest)
                                    .subscribe(newEvent => {
                                        if (newEvent instanceof HttpResponse) {
                                            // the second try went well and we have valid response
                                            // give response to user and complete the subscription
                                            subscriber.next(newEvent);
                                            subscriber.complete();
                                        }
                                    }, error => {
                                        // second try went wrong -> throw error to subscriber
                                        subscriber.error(error);
                                    });
                            });
                        } else {
                            // the error was not related to auth token -> throw error to subscriber
                            subscriber.error(error);
                        }
                    });
        });

    }

    /**
     * Try to re-login the user.
     */
    private reLogin(): Observable {
        // obtain new authorization token and return it
    }
}