angular-7-interceptor-retry-requests-after-token-refresh

Question

I am trying to implement an interceptor for failed requests in case of a token expired. I have tried multiple approaches but still no success.

I have referred below URL & read multiple blogs. everyone is suggesting switch map approach but not working with me. Angular 4 Interceptor retry requests after token refresh

I have tried collecting all request into cachedRequests: Array> = []; but not idea how to use it for re trigger failed requests .

this.next.handle(request) is not recalling after successful refreshtoken. I can see the updated request object though.

can someone please point to where to refer in angular 7 with
"rxjs": "~6.3.3", "rxjs-compat": "^6.5.2", to implement interceptor.

Below is the code working for me but getting response of token only

``````````
    handleError(request: HttpRequest<any>, next: HttpHandler, err) {
            if (err instanceof HttpErrorResponse) {
                if (err.status === 401) {
                    this.service.getNewToken().pipe(filter(token => token != null),
                        take(1),
                        switchMap((token: any) => {
                            console.log('token', token);
                            if (token && token.access_token && token.refresh_token) {
                                sessionStorage.setItem('accessToken', token.access_token);
                                sessionStorage.setItem('refreshToken', token.refresh_token);
                            }
                            request = this.addHeader(request);
                            request.headers.getAll('Authorization');
                            return next.handle(request);
                        })).subscribe(results => this.subject.next(results));

                }
            }
        }

`````````

Update 2: after trying multiple approaches I have found

return next.handle(request); <-- this is simply not getting called
return next.handle(request).subscribe(); <-- this is getting called but not updating response to requested component.

pointers appreciated

nitin1416 · Accepted Answer · 2020-01-31T13:21:25.320

Replying late. this is how I did it.

Works with parallel request as well.

import { HttpInterceptor, HttpRequest, HttpHandler, HttpErrorResponse, HttpEvent, HttpResponse } from '@angular/common/http';
import { Injectable } from '@angular/core';
import { environment } from 'src/environments/environment';
import { GlobalService } from './global.service';
import { tap, mergeMap, switchMap, filter, take, flatMap, catchError } from 'rxjs/operators';
import { Observable, Subject, throwError, of, BehaviorSubject } from 'rxjs';


@Injectable()
export class InterceptorService implements HttpInterceptor {
    private isRefreshing = false;
    private refreshTokenSubject: BehaviorSubject<any> = new BehaviorSubject<any>(null);
    constructor(public globalService: GlobalService) {
    }

    intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        request = this.addHeader(request);
        // console.log('request ', request);
        return next.handle(request).pipe(catchError((error: any) => {
            if (error instanceof HttpErrorResponse) {
                if (error.status === 401) {
                    if (!this.isRefreshing) {
                        this.isRefreshing = true;
                        this.refreshTokenSubject.next(null);
                        request = this.addHeader(request);
                        console.log('Token request');
                        return this.globalService.getRefershToken().pipe(
                            switchMap((token: any) => {
                                console.log('inside token');
                                this.isRefreshing = false;

                                if (token && token.access_token && token.refresh_token) {
                                    sessionStorage.setItem('accessToken', token.access_token);
                                    sessionStorage.setItem('refreshToken', token.refresh_token);
                                }
                                // request = this.addHeader(request);
                                // console.log('request: ', request);
                                this.refreshTokenSubject.next(token);
                                return next.handle(this.addHeader(request));
                            }));

                    } else {
                        console.log('inside else call');
                        console.log('token : ', this.refreshTokenSubject.getValue());
                        return this.refreshTokenSubject.pipe(
                            filter(token => (token != null && token != undefined)),
                            take(1),
                            switchMap(() => {
                                console.log('adding header in else');
                                return next.handle(this.addHeader(request))

                            }));
                    }
                }
            }
        }));
    }

    private addHeader(request: HttpRequest<any>) {
        let getEndPoint = request.url.split('/')[request.url.split('/').length - 1];
        if (getEndPoint !== 'refreshToken') {
            const accessToken = sessionStorage.getItem('accessToken');
            request = request.clone({
                setHeaders: {
                    Authorization: `Bearer ${accessToken}`
                }
            });
        } else if (getEndPoint === 'refreshToken') {
            const refreshToken = sessionStorage.getItem('refreshToken');
            request = request.clone({
                setHeaders: {
                    applicationCode: environment.applicationCode,
                    'refresh-token': `${refreshToken}`,
                }
            });
        }
        return request;
    }
}

score 0 · Answer 2 · answered Aug 22 '22 at 15:13

After api failed with HTTP Error 401 ,token-refresh api got called , all your failed and cached request can be retried using http interceptor.

if (this.isRefreshingToken && !req.url.endsWith(tokenURL)) {
      // check if unique url to be added in cachedRequest

      if (urlPresentIndex == -1) {
        this.cachedRequests.push(req);
        return this.tokenSubject.pipe(
          switchMap(() => next.handle(req)),
          tap((v) => {
            // delete request from catchedRequest if api gets called

            this.cachedRequests.splice(
              this.cachedRequests.findIndex(
                (httpRequest) => httpRequest.url == req.url
              ),
              1
            );
            return EMPTY;
          })
        );
      } else {
        //already in cached request array

        return EMPTY;
      }
    }

For more details you can read my medium article Token-Refresh-Interceptor-retry-failed-Requests

Check it out, how it works stackblitz

angular-7-interceptor-retry-requests-after-token-refresh

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