I am trying to use an interceptor to handle http errors and retry for a special error status, in my case the status code 502.
intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
return next.handle(request)
.pipe(
retryWhen(errors => {
return errors
.pipe(
mergeMap(error => (error.status === 502) ? throwError(error) : of(error)),
take(2)
)
})
)
}
But it's not working, whereas when I am using retry()
in this fashion, it's working perfectly
intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
return next.handle(request)
.pipe(
retry(2),
catchError((error: HttpErrorResponse) => {
return throwError(error);
})
)
}
I took your approach and expanded it a little, out of own interest.
The first would be to create a sort of custom operator:
import { timer, throwError, Observable } from 'rxjs';
import { mergeMap } from 'rxjs/operators';
export interface RetryParams {
maxAttempts?: number;
scalingDuration?: number;
shouldRetry?: ({ status: number }) => boolean;
}
const defaultParams: RetryParams = {
maxAttempts: 3,
scalingDuration: 1000,
shouldRetry: ({ status }) => status >= 400
}
export const genericRetryStrategy = (params: RetryParams = {}) => (attempts: Observable<any>) => attempts.pipe(
mergeMap((error, i) => {
const { maxAttempts, scalingDuration, shouldRetry } = { ...defaultParams, ...params }
const retryAttempt = i + 1;
// if maximum number of retries have been met
// or response is a status code we don't wish to retry, throw error
if (retryAttempt > maxAttempts || !shouldRetry(error)) {
return throwError(error);
}
console.log(`Attempt ${retryAttempt}: retrying in ${retryAttempt * scalingDuration}ms`);
// retry after 1s, 2s, etc...
return timer(retryAttempt * scalingDuration);
})
);
You can then construct an interceptor based on this operator as follows:
@Injectable()
export class RetryInterceptor implements HttpInterceptor {
intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
const { shouldRetry } = this;
return next.handle(request)
.pipe(retryWhen(genericRetryStrategy({
shouldRetry
})));
}
private shouldRetry = (error) => error.status === 502;
}
You can see it working in this blitz