`useQuery` with `initialData` is returning `undefined` data when another query with the same key a no `initialData` is fetching about query HOT 3 CLOSED

oh interesting. So conceptually, I think this is how it's designed to work. initialData is only taken into account when the Query is created in the cache, which in your case happens when you call prefetchQuery.

When your component renders, it will pick up the already existing Query and initialData is ignored.

So overall, this is a typings issue at best. I was very reluctant to add any guarantees on data always being defined, and really thought that when initialData is provided, nothing can go wrong. But I guess there are cases like the one you've described.

However, I don't think we're going back on the type definitions to make them T | undefined even if initialData is provided. It's too good of a dx improvement 99% of the time.

What you probably want in your case is placeholderData, which is always taken in to account and doesn't narrow the type.

https://codesandbox.io/p/sandbox/react-query-with-initial-data-forked-whffv2

from query.

well with queryOptions, we can infer the return type when a key is used depending on what the quryFn returns. But that doesn't help us with adding | undefined to the union or not

from query.

Interesting discussion.

Since this is a typings issue, I do wonder if there's some consideration to infer return type based on the query key? Perhaps this already digresses to a discussion on key management, but I do believe that in almost all cases, the expectation would be that a single return type exists given a key, regardless of that key being used in prefetchQuery or useQuery.

from query.