useQuery does not return data on refetch after error.

[rostero1]

Steps to reproduce:

1. Make a successful request
2. Take graphql server offline
3. Make a new request
4. We get an error now.
5. Take graphql server online
6. Invoke refetch.
7. Note the successful network request in devtools, but we never get data back from useQuery.

[maxguzenski]

This issue happen on my own apollo hook implementation as well. The solution is re-subscribe to watched query after an error. I believe it is an apollo-client core issue.

useEffect(() => {
  const subscribe = watchedQuery.subscribe({...}) 
  return () => subscribe.unsubscribe()
}, [...othersVariablesToCheck, error]) // <- this

[maxguzenski]

My mistake. Only re-subscribe dont fix this issue https://github.com/apollographql/react-apollo/issues/2070

My work around now is rebuild client.watchQuery after a refetch with error.

[maxguzenski]

I was able to solve the problem based on https://github.com/apollographql/react-apollo/blob/master/src/Query.tsx#L363

changing useEffect inside useQuery by:

  useEffect(() => {
    if (!watchedQuery) {
      return 
    }

    let subscription

    // if fetchPolicy='cache-and-network' and data is on cache
    // notifyOnNetworkStatusChange is aways TRUE, why?? 
    // this "if" fix it.
    function invalidateCurrentResult(props) {
      if (props.loading) return
      setResponseID(x => x + 1)
    } 

    // from: https://github.com/apollographql/react-apollo/blob/master/src/Query.tsx#L363
    // after a error on refetch, without this fix, refetch never works again
    function invalidateErrorResult() {
      unsubscribe()

      const lastError  = watchedQuery.getLastError()
      const lastResult = watchedQuery.getLastResult()

      watchedQuery.resetLastResults()
      subscribe() 

      Object.assign(watchedQuery, { lastError, lastResult })
      setResponseID(x => x + 1)
    }

    function subscribe() {
      subscription = watchedQuery.subscribe(
        invalidateCurrentResult,
        invalidateErrorResult
      )
    }

    function unsubscribe() {
      if (subscription) subscription.unsubscribe() 
      subscription = undefined
    }

    subscribe()
    return unsubscribe

  }, [watchedQuery])

[trojanowski]

@maxguzenski Thank you for the info. Would you like to prepare a PR?

[pontusab]

@maxguzenski Would really want a PR for this too 💯

[maxguzenski]

I'm on vacation until March, 25 ... I can not do a PR until that date.

[pontusab]

@maxguzenski Have a great vacation, I will make a PR with your solution. Thanks 🥇

[gregbty]

I'm assuming a PR is still needed for this? Running into this issue now and it is still unresolved in react-apollo so thought it would probably be easier to apply the workaround above in this repo. I can open one if needed.