angular - Change header on HTTP before retrying an Observable -

i using angular 2 typescript on front-end. trying implement http interceptor setting authorization header on each request. if access token expires trying retry request, new access token refresh token , change header of current request, before retry.

how update request header in retrywhen operator?

for example here httpinterceptor:

export class httpinterceptor extends http {     get(url: string, options?: requestoptionsargs): observable<response> {         return super.get(url, this.setrequestauthorizationheader(options)).retrywhen((errors: any) => this.errorhandler(errors));     }      private setrequestauthorizationheader(options?: requestoptionsargs): requestoptionsargs {         // checks         // accesstoken localstorage         options.headers.append('authorization', 'bearer ' + accesstoken);     }      private errorhandler(errors) {         return errors.switchmap((err) => {         if (err.status === 401) {             let closedsubject = new subject();              this.authenticationservice.refreshtoken()                 .subscribe(data => {                     // how update authorization header? doesn't work.                     this.defaultoptions.headers.append('authorization', 'bearer ' + data.accesstoken);                      closedsubject.next();                 });              return <any>closedsubject;         }         else {             return observable.throw(err.json());         }     }); } } 

i use catch instead of retrywhen latter 1 replay same observable, , parameters have been set.

btw, subject useless in errorhanlder :

export class httpinterceptor extends http {   get(url: string, options ? : requestoptionsargs): observable < response > {     return super.get(url, this.setrequestauthorizationheader(options)).catch(errors => this.errorhandler(errors, url, options))   }); }  private setrequestauthorizationheader(options ? : requestoptionsargs): requestoptionsargs {   // checks   // accesstoken localstorage   options.headers.append('authorization', 'bearer ' + accesstoken);   return options }  private errorhandler(err: any, url: string, options ? : requestoptionsargs) {   if (err.status === 401) {     return this.authenticationservice.refreshtoken()       .switchmap(data => {           // save accesstoken localstorage           return super.get(url, this.setrequestauthorizationheader(options));       });   }   return observable.throw(err.json()); } 

also note using state this.defaultoptions not best choice, using anobservable more appropriate.