onSuccess is only triggered once?

[joshkel]

Bug report

Description / Observed Behavior

Our application uses onSuccess to trigger certain desired behavior. However, in testing, it appears that onSuccess is only triggered if that specific useSWR call is responsible for the success - if the data was already loaded from another useSWR call, it's not triggered.

Expected Behavior

onSuccess is triggered whenever data is successfully available, whether that successful request came from this instance or another.

Repro Steps / Code Example

https://codesandbox.io/s/swr-on-success-uuigol?file=/src/App.tsx

Additional Context

SWR version: 2.1.1

[promer94]

Thanks for reporting and reproduction !

This is currently a expected behavior since SWR will deduplicate the requests so only one request will be executed and trigger the onSuccess callback once. #1580

You could use useEffect as alternative.

const { data } = useSWR('api', fetcher)
React.useEffect(() => {
    if (data)
      //do something
    }
}, [data])

[Marcosld]

Thanks for reporting and reproduction !

This is currently a expected behavior since SWR will deduplicate the requests so only one request will be executed and trigger the onSuccess callback once. #1580

You could use useEffect as alternative.

const { data } = useSWR('api', fetcher)
React.useEffect(() => {
    if (data)
      //do something
    }
}, [data])

Is it guaranteed that the data object reference will be the same between renders so that hook doesn't get executed until there's a new request (for example when using immutable swr hooks)?