Angular HTTP interceptor for Authentication header

Question

I have to put a token inside the 'Authorization' header for every HTTP request. So I have developed and registered an HttpInterceptor :

@Injectable()
export class TokenInterceptor implements HttpInterceptor {

  constructor(public authService: AuthService) {
  }  

  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {

    let modifiedReq;
    const token = this.authService.getToken();

    // we need the heck clone because the HttpRequest is immutable
    // https://angular.io/guide/http#immutability
    if (token) {
      modifiedReq = request.clone();
      modifiedReq.headers.set('Authorization', `Bearer ${token}`);
    }

    return next.handle(modifiedReq ? modifiedReq : request).pipe(tap(() => {
        // do nothing
    },
    (err: any) => {
    if (err instanceof HttpErrorResponse) {
      if (err.status === 0) {
        alert('what the heck, 0 HTTP code?');
      }
      if (err.status !== 401) {
        return;
      }
      this.authService.goToLogin();
    }
  }));
 }
}

But the header seems never to be put on the request sent. What am I doing wrong?

Also, sometimes an errorcode '0' gets caught by the interceptor; what does it mean?

Angular 8.2.11

EDIT 1: ------------------------

I've also tried like this:

request = request.clone({
            setHeaders: {
                authorization: `Bearer ${token}`
            }
        });

but still no header has been set. Also, the module is correctly registered in app.module

 providers: [{
   provide: HTTP_INTERCEPTORS,
   useClass: TokenInterceptor ,
   multi: true,
 }..

EDIT 2 : ------------------------

Check this image... I'm going crazy.

lovis91 lovis91 · Accepted Answer · 2020-02-21T15:02:14

It's working for me like this:

const headersConfig = {
  'Accept': 'application/json', //default headers
};
...

if (token) {
  headersConfig['Authorization'] = `Bearer ${token}`;
}
...

return next
  .handle(request.clone({
     setHeaders: headersConfig
  }))

Angular HTTP interceptor for Authentication header

3 Answers