snapshot of https://github.com/TanStack/query.git (main, 2026-09-16; blobs > 131072B omitted)

docs/framework/lit/reference/functions/hydrate.md

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+---
+id: hydrate
+title: hydrate
+---
+
+```ts
+function hydrate(
+   client,
+   dehydratedState,
+   options?): void;
+```
+
+Defined in: [packages/query-core/src/hydration.ts:264](https://github.com/TanStack/query/blob/main/packages/query-core/src/hydration.ts#L264)
+
+Restores a `DehydratedState` (as produced by `dehydrate`) into a `QueryClient`'s cache, typically to seed the
+client with data already fetched on the server. `mutations` and `queries` are each optional on `dehydratedState`.
+Queries not yet in the cache are built from the dehydrated snapshot; queries that already exist are only updated
+when the dehydrated data is newer than what's already cached. Newly built queries have their `fetchStatus` reset
+to `'idle'` so they don't hydrate stuck in a fetching state. If a dehydrated query still had an in-flight
+promise, it is resumed via `query.fetch()` (reusing that promise as `initialPromise`) rather than re-invoking
+`queryFn`.
+
+## Parameters
+
+### client
+
+[`QueryClient`](../classes/QueryClient.md)
+
+### dehydratedState
+
+`Partial`\<[`DehydratedState`](../interfaces/DehydratedState.md)\>
+
+### options?
+
+[`HydrateOptions`](../interfaces/HydrateOptions.md)
+
+## Returns
+
+`void`
+
+## Example
+
+```ts
+// dehydratedState was produced by `dehydrate` on the server
+// and sent to the client, e.g. embedded in server-rendered markup.
+const queryClient = new QueryClient()
+
+hydrate(queryClient, dehydratedState)
+```