RxJS catch and retry an Observable

Question

My use case is to map an Observable to redux actions of success and failure. I make a network call (with a function that gives promise), if it succeeds I have to forward a success action, if it fails than an error action. The Observable itself shall keep going. For all I could search, RxJS do not have a mechanism for this catching the error and retrying the original. I have following solution in my code which I am not happy with:

error$ = new Rx.Subject();

searchResultAction$ = search$
    .flatMap(getSearchResultsPromise)
    .map((resuls) => {
        return {
            type: 'SUCCESS_ACTION',
            payload: {
                results
            }
        }
    })
    .retryWhen((err$) => {
        return err$
            .pluck('query')
            .do(error$.onNext.bind(error$));
    });

searchErrorAction$
    .map((query) => {
        return {
            type: 'ERROR_ACTION',
            payload: {
                query,
                message: 'Error while retrieving data'
            }
        }
    });

action$ = Observable
    .merge(
        searchResultAction$,
        searchErrorAction$
    )
    .doOnError(err => console.error('Ignored error: ', err))
    .retry();

action$.subscribe(dispatch);

i.e I create a subject, and push errors into that subject and create an Observable of error actions from that.

Is there a better alternative of doing this in RxJS that I am missing? Basically I want to emit a notification of what error has occurred, and then continue with whatever the Observable is already doing.

Brandon Brandon · Accepted Answer · 2015-11-24T16:44:53

This would retry failed queries:

var action$ = search$
    .flatMap(value => {
        // create an observable that will execute
        // the query each time it is subscribed
        const query = Rx.Observable.defer(() => getSearchResultsPromise(value));

        // add a retry operation to this query
        return query.retryWhen(errors$ => errors$.do(err => {
            console.log("ignoring error: ", err);
        }));
    })
    .map(payload => ({ type: "SUCCESS_ACTION", payload }));

action$.subscribe(dispatcher);

If you don't want to retry, but just want to notify or ignore errors:

var action$ = search$
    .flatMap(value => {
        // create an observable that will execute
        // the query each time it is subscribed
        const query = Rx.Observable.defer(() => getSearchResultsPromise(value));

        // add a catch clause to "ignore" the error
        return query.catch(err => {
            console.log("ignoring error: ", err);
            return Observable.empty(); // no result for this query
        }));
    })
    .map(payload => ({ type: "SUCCESS_ACTION", payload }));

action$.subscribe(dispatcher);

RxJS catch **and** retry an Observable

1 Answers

RxJS catch and retry an Observable