503 HTTP Code - Retry-After header

[uwinkler]

Hi,

I was wondering if useQuery is handling 503 HTTP errors. In particular the retry option.

https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/503

Common causes are a server that is down for maintenance or that is overloaded. This response should be used for temporary conditions and the Retry-After HTTP header should, if possible, contain the estimated time for the recovery of the service.

Is tanstack query handling that header as intended?

[TkDodo]

TanStack Query doesn't make requests - it manages promises. So no, it doesn't automatically handle HTTP status codes because you can write a queryFn that is simply: queryFn: () => Promise.resolve(23). It's not tied to anything HTTP, it's not tied to graphQL - it's only tied to Promises.

So if you want to handle http headers, you need to extract the headers from the response (depending on how YOU do http requests, because TanStack Query doesn't make the request), return it from queryFn alongside your data or as part of your error (more likely with 503) and then implement the retry function to act according to that information.

[uwinkler]

Thank you! Sorry.. my question was not very specific and a bit miss-leading. So i guess I could use the retrayDelay function such that the fetch should throw an error and that error would than be the TError that the retryDelay would get, right?

retryDelay: number | (retryAttempt: number, error: TError) => number

[TkDodo]

yes