Angular httpClient interceptor error handling

Question

after reading the documentation on angular about http client error handling, I still don\'t understand why I don\'t catch a 401 error from the server with the code below:

<

Answer 1

here some example I'm using:

export class ErrorHandlerInterceptor implements HttpInterceptor {

    intercept(
        request: HttpRequest<any>,
        next: HttpHandler
    ): Observable<HttpEvent<any>> {
        const loadingHandlerService = this.inej.get(LoadingHandlerService);
        const errorHandlerService = this.inej.get(ErrorHandlerService);

        return next.handle(request)
            .pipe(
                catchError(err => {
                    loadingHandlerService.hideLoading();
                    if (err instanceof HttpErrorResponse) { errorHandlerService.handleError(err) }
                    return new Observable<HttpEvent<any>>();
                })
            );
    }

    constructor(private inej: Injector) { }
}

Answer 2

You must pass the argument value to the do function of the stream, not create a new function inside it:

return next.handle(request)
    .do((err: any) => {
        console.log('this log isn't');
        if (err instanceof HttpErrorResponse) {
            if (err.status === 401) {
                console.log('nor this one!');
            }
        }
    });

Answer 3

Your error handler needs to return a new Observable<HttpEvent<any>>()

return next.handle(request)
    .pipe(catchError((err: any) => {
        console.log('this log isn't');
        if (err instanceof HttpErrorResponse) {
            if (err.status === 401) {
                console.log('Unauthorized');
            }
        }

      return new Observable<HttpEvent<any>>();
    }));

Answer 4

It is off top, but Angular has better opportunity handle errors than interceptor. You can implement your own ErrorHandler. https://angular.io/api/core/ErrorHandler

Answer 5

You should catch an error using catchError

return next.handle(request)
      .pipe(catchError(err => {
        if (err instanceof HttpErrorResponse) {
            if (err.status === 401) {
                console.log('this should print your error!', err.error);
            }
        }
}));