Return type of data when placeholderData is provided

[zachdtaylor]

I noticed that even when placeholderData is provided as a useQuery option, the data attribute on the result can still be undefined according to TypeScript. Is that accurate? I thought the data attribute would never be undefined if placeholderData was provided. For example, if I do

const { data } = useQuery<string>('key', () => fetch('/get-string'), { placeholderData: 'Loading...' })

the type of data is string | undefined, but I thought it should just be string or maybe string | 'Loading...'.

[TkDodo]

Yes, it’s a request that comes up a lot, but neither placeholderData nor initialData can currently narrow the type.