Retrying network request for set amount of time

Hey, I understand this is a “how to” question, and this might not be the place for it. If so, feel free to close ticket, and I’ll open elsewhere.

I’m implementing payments against a very retro (I’m being nice here 😉 ) API, and can’t rely on the redirect after payment to contain the correct status. After payment, the payment provider makes a callback to a URL specified by us, which updates the order, which I have to check against. What I’d like to achieve in a semi-sensible way is this:

• User lands on page, start saga
• For 10 seconds (a race I imagine), call the order endpoint every 2 seconds to see if the order has the correct status
• If the request “fails” (promise rejects), keep retrying
• If the request “succeeds” (promise resolves), end race
• After 10 seconds, if the request hasn’t succeeded, assume “fails”.

I understand the race concept and have implemented it elsewhere, I’m just not sure how to do the “retry every 2 seconds” and fit it in there. Any thoughts?

If you feel this warrants an extra page under “Advanced Concepts” I’d be happy to write it and contribute it back.

[yelouafi]

You’ll have to throw the error instead of returing it

function* checkOrderSaga() {
  for(let i = 1; i <= 5; i++) {
    try {
      const order = yield call(orderApi);
      return order;
    } catch(err) {
      if(i < 5) {
        yield call(delay, 2000);
      }
    }
  }
  // attempts failed after 5x2secs
  throw new Error('Order not fulfilled. Giving up.');
}

EDIT the code return Error was just for illustration

[yelouafi]

yes; throwing instead of returning is because you catch in the containing saga, so you’re expecting the subsaga to throw errors instead of returning them