Invalidate after mutation

React chapter 28 · TanStack Query · invalidateQueries · source: TanStack/query/packages/query-core/src/queryClient.ts

The problem

You POST a todo, then the list still shows the old cache until a full page reload. Fetch-on-mount is not enough — the cache is stale-while-revalidate, and nobody told it to refetch.

The pattern that fixes it

mutation.mutate() then queryClient.invalidateQueries({ queryKey: ["todos"] }). Observers refetch. The list can keep showing the old data (SWR) until the new payload arrives.

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