tanstack-query

Migrate to v5 by switching all hooks to object syntax, replacing cacheTime with gcTime, using isPending instead of isLoading for initial loads, and moving query onSuccess callbacks into useEffect. Infinite queries also require an explicit initialPageParam option.

In v5, isLoading now means isPending AND isFetching, so it behaves differently than v4. Use isPending to detect the initial loading state when no data exists yet, which matches the old v4 isLoading behavior.

Hydration errors with server-side prefetching occur because useQuery can resolve synchronously during hydration. Use useSuspenseQuery instead of useQuery for SSR, or await the prefetch call rather than using the void prefetch pattern.

Yes, v5 supports both traditional cache-manipulation optimistic updates with onMutate rollback and a simplified pattern using useMutationState to render pending mutation variables directly. The simplified approach requires no cache manipulation or rollback logic.

Version 5.89.0 added an onMutateResult parameter between variables and context in mutation callbacks, changing signatures from three to four parameters. Update onSuccess and onError callbacks to accept (data, variables, onMutateResult, context).

Do not use TanStack Query for client-only state like modal visibility or form inputs; use useState or a client state library instead. It is designed specifically for server state that lives on a remote API and needs caching, deduplication, and synchronization.