[Bug] `loading` doesn't change back to false if updateQuery doesn't mutate the store

I was dealing with pagination in an app and I forgot to update my hasNextPage field which caused a call to fetchMore which returned an empty array (because the connection had no more edges). When I proceeded to merge this with my previous result, the loading prop didn’t change to false after the APOLLO_UPDATE_QUERY_RESULT was fired.

I tried to reproduce the error by simply returning previousResult from updateQuery. Funnily enough, the error was only happening when I included pagination variables. This leads me to believe that the bug only occurs when APOLLO_QUERY_RESULT changes but APOLLO_QUERY_UPDATE_RESULT doesn’t update the store.

Here is a snippet of my code (I changed some variable names for clarity):

// repro
fetchMore({
  variables: { after: connection.pageInfo.endCursor },
  updateQuery: (previousResult, { fetchMoreResult: { data } }) => previousResult,
});

If variables is removed (or after), the bug will stop occurring. If after is removed, but first is added (thus changing APOLLO_QUERY_RESULT but NOT APOLLO_UPDATE_QUERY_RESULT) then the bug will start occurring again.

tl;dr: If updateQuery results in a different query being fetched but it returns the previous result, loading will never be set to false even after both APOLLO_QUERY_RESULT and APOLLO_QUERY_UPDATE have been fired.

EDIT: FYI, our GraphQL backend uses the Relay Cursor Connections Specification for pagination.

[helfer]

Thanks, that sounds like it could be a bug. We’ll probably take care of this when we refactor the loading state in the next few weeks.

cc @tmeasday

[migueloller]

@tmeasday, I am using react-apollo. Sorry for the misunderstanding.

I’ve split the issue into two separate ones as needed. Closing this one.