feat: add support for React.use()

docs/framework/react/guides/suspense.md

@@ -8,6 +8,7 @@ React Query can also be used with React's Suspense for Data Fetching API's. For
 - [useSuspenseQuery](../../reference/useSuspenseQuery)
 - [useSuspenseInfiniteQuery](../../reference/useSuspenseInfiniteQuery)
 - [useSuspenseQueries](../../reference/useSuspenseQueries)
+- Additionally, you can use the `useQuery().promise` and `React.use()` (Experimental)
 
 When using suspense mode, `status` states and `error` objects are not needed and are then replaced by usage of the `React.Suspense` component (including the use of the `fallback` prop and React error boundaries for catching errors). Please read the [Resetting Error Boundaries](#resetting-error-boundaries) and look at the [Suspense Example](https://stackblitz.com/github/TanStack/query/tree/main/examples/react/suspense) for more information on how to set up suspense mode.
 
@@ -172,3 +173,52 @@ export function Providers(props: { children: React.ReactNode }) {
 ```
 
 For more information, check out the [NextJs Suspense Streaming Example](../../examples/nextjs-suspense-streaming) and the [Advanced Rendering & Hydration](../advanced-ssr) guide.
+
+## Using `useQuery().promise` and `React.use()` (Experimental)
+
+> To enable this feature, you need to set the `experimental_prefetchInRender` option to `true` when creating your `QueryClient`
+
+**Example code:**
+
+```tsx
+const queryClient = new QueryClient({
+  defaultOptions: {
+    queries: {
+      experimental_prefetchInRender: true,
+    },
+  },
+})
+```
+
+**Usage:**
+
+```tsx
+import React from 'react'
+import { useQuery } from '@tanstack/react-query'
+import { fetchTodos, type Todo } from './api'
+
+function TodoList({ query }: { query: UseQueryResult<Todo[]> }) {
+  const data = React.use(query.promise)
+
+  return (
+    <ul>
+      {data.map((todo) => (
+        <li key={todo.id}>{todo.title}</li>
+      ))}
+    </ul>
+  )
+}
+
+export function App() {
+  const query = useQuery({ queryKey: ['todos'], queryFn: fetchTodos })
+
+  return (
+    <>
+      <h1>Todos</h1>
+      <React.Suspense fallback={<div>Loading...</div>}>
+        <TodoList query={query} />
+      </React.Suspense>
+    </>
+  )
+}
+```

docs/framework/react/reference/queryOptions.md

@@ -17,3 +17,8 @@ You can generally pass everything to `queryOptions` that you can also pass to [`
 - `queryKey: QueryKey`
   - **Required**
   - The query key to generate options for.
+- `experimental_prefetchInRender?: boolean`
+  - Optional
+  - Defaults to `false`
+  - When set to `true`, queries will be prefetched during render, which can be useful for certain optimization scenarios
+  - Needs to be turned on for the experimental `useQuery().promise` functionality

docs/framework/react/reference/useInfiniteQuery.md

@@ -11,6 +11,7 @@ const {
   hasPreviousPage,
   isFetchingNextPage,
   isFetchingPreviousPage,
+  promise,
   ...result
 } = useInfiniteQuery({
   queryKey,
@@ -85,5 +86,9 @@ The returned properties for `useInfiniteQuery` are identical to the [`useQuery`
   - Is the same as `isFetching && !isPending && !isFetchingNextPage && !isFetchingPreviousPage`
 - `isRefetchError: boolean`
   - Will be `true` if the query failed while refetching a page.
+- `promise: Promise<TData>`
+  - A stable promise that resolves to the query result.
+  - This can be used with `React.use()` to fetch data
+  - Requires the `experimental_prefetchInRender` feature flag to be enabled on the `QueryClient`.
 
 Keep in mind that imperative fetch calls, such as `fetchNextPage`, may interfere with the default refetch behaviour, resulting in outdated data. Make sure to call these functions only in response to user actions, or add conditions like `hasNextPage && !isFetching`.

docs/framework/react/reference/useQuery.md

@@ -26,6 +26,7 @@ const {
   isRefetching,
   isStale,
   isSuccess,
+  promise,
   refetch,
   status,
 } = useQuery(
@@ -244,3 +245,6 @@ const {
     - Defaults to `true`
       - Per default, a currently running request will be cancelled before a new request is made
     - When set to `false`, no refetch will be made if there is already a request running.
+- `promise: Promise<TData>`
+  - A stable promise that will be resolved with the data of the query.
+  - Requires the `experimental_prefetchInRender` feature flag to be enabled on the `QueryClient`.

packages/query-core/src/__tests__/queryObserver.test.tsx

@@ -16,7 +16,13 @@ describe('queryObserver', () => {
   let queryClient: QueryClient
 
   beforeEach(() => {
-    queryClient = createQueryClient()
+    queryClient = createQueryClient({
+      defaultOptions: {
+        queries: {
+          experimental_prefetchInRender: true,
+        },
+      },
+    })
     queryClient.mount()
   })
 
@@ -1133,4 +1139,98 @@ describe('queryObserver', () => {
 
     unsubscribe()
   })
+
+  test('should return a promise that resolves when data is present', async () => {
+    const results: Array<QueryObserverResult> = []
+    const key = queryKey()
+    let count = 0
+    const observer = new QueryObserver(queryClient, {
+      queryKey: key,
+      queryFn: () => {
+        if (++count > 9) {
+          return Promise.resolve('data')
+        }
+        throw new Error('rejected')
+      },
+      retry: 10,
+      retryDelay: 0,
+    })
+    const unsubscribe = observer.subscribe(() => {
+      results.push(observer.getCurrentResult())
+    })
+
+    await waitFor(() => {
+      expect(results.at(-1)?.data).toBe('data')
+    })
+
+    const numberOfUniquePromises = new Set(
+      results.map((result) => result.promise),
+    ).size
+    expect(numberOfUniquePromises).toBe(1)
+
+    unsubscribe()
+  })
+
+  test('should return a new promise after recovering from an error', async () => {
+    const results: Array<QueryObserverResult> = []
+    const key = queryKey()
+
+    let succeeds = false
+    let idx = 0
+    const observer = new QueryObserver(queryClient, {
+      queryKey: key,
+      queryFn: () => {
+        if (succeeds) {
+          return Promise.resolve('data')
+        }
+        throw new Error(`rejected #${++idx}`)
+      },
+      retry: 5,
+      retryDelay: 0,
+    })
+    const unsubscribe = observer.subscribe(() => {
+      results.push(observer.getCurrentResult())
+    })
+
+    await waitFor(() => {
+      expect(results.at(-1)?.status).toBe('error')
+    })
+
+    expect(
+      results.every((result) => result.promise === results[0]!.promise),
+    ).toBe(true)
+
+    {
+      // fail again
+      const lengthBefore = results.length
+      observer.refetch()
+      await waitFor(() => {
+        expect(results.length).toBeGreaterThan(lengthBefore)
+        expect(results.at(-1)?.status).toBe('error')
+      })
+
+      const numberOfUniquePromises = new Set(
+        results.map((result) => result.promise),
+      ).size
+
+      expect(numberOfUniquePromises).toBe(2)
+    }
+    {
+      // succeed
+      succeeds = true
+      observer.refetch()
+
+      await waitFor(() => {
+        results.at(-1)?.status === 'success'
+      })
+
+      const numberOfUniquePromises = new Set(
+        results.map((result) => result.promise),
+      ).size
+
+      expect(numberOfUniquePromises).toBe(3)
+    }
+
+    unsubscribe()
+  })
 })

packages/query-core/src/queryObserver.ts

@@ -1,3 +1,8 @@
+import { focusManager } from './focusManager'
+import { notifyManager } from './notifyManager'
+import { fetchState } from './query'
+import { Subscribable } from './subscribable'
+import { pendingThenable } from './thenable'
 import {
   isServer,
   isValidTimeout,
@@ -8,12 +13,9 @@ import {
   shallowEqualObjects,
   timeUntilStale,
 } from './utils'
-import { notifyManager } from './notifyManager'
-import { focusManager } from './focusManager'
-import { Subscribable } from './subscribable'
-import { fetchState } from './query'
 import type { FetchOptions, Query, QueryState } from './query'
 import type { QueryClient } from './queryClient'
+import type { PendingThenable, Thenable } from './thenable'
 import type {
   DefaultError,
   DefaultedQueryObserverOptions,
@@ -57,6 +59,7 @@ export class QueryObserver<
     TQueryData,
     TQueryKey
   >
+  #currentThenable: Thenable<TData>
   #selectError: TError | null
   #selectFn?: (data: TQueryData) => TData
   #selectResult?: TData
@@ -82,6 +85,13 @@ export class QueryObserver<
 
     this.#client = client
     this.#selectError = null
+    this.#currentThenable = pendingThenable()
+    if (!this.options.experimental_prefetchInRender) {
+      this.#currentThenable.reject(
+        new Error('experimental_prefetchInRender feature flag is not enabled'),
+      )
+    }
+
     this.bindMethods()
     this.setOptions(options)
   }
@@ -582,6 +592,7 @@ export class QueryObserver<
       isRefetchError: isError && hasData,
       isStale: isStale(query, options),
       refetch: this.refetch,
+      promise: this.#currentThenable,
     }
 
     return result as QueryObserverResult<TData, TError>
@@ -593,6 +604,7 @@ export class QueryObserver<
       | undefined
 
     const nextResult = this.createResult(this.#currentQuery, this.options)
+
     this.#currentResultState = this.#currentQuery.state
     this.#currentResultOptions = this.options
 
@@ -605,6 +617,52 @@ export class QueryObserver<
       return
     }
 
+    if (this.options.experimental_prefetchInRender) {
+      const finalizeThenableIfPossible = (thenable: PendingThenable<TData>) => {
+        if (nextResult.status === 'error') {
+          thenable.reject(nextResult.error)
+        } else if (nextResult.data !== undefined) {
+          thenable.resolve(nextResult.data)
+        }
+      }
+
+      /**
+       * Create a new thenable and result promise when the results have changed
+       */
+      const recreateThenable = () => {
+        const pending =
+          (this.#currentThenable =
+          nextResult.promise =
+            pendingThenable())
+
+        finalizeThenableIfPossible(pending)
+      }
+
+      const prevThenable = this.#currentThenable
+      switch (prevThenable.status) {
+        case 'pending':
+          // Finalize the previous thenable if it was pending
+          finalizeThenableIfPossible(prevThenable)
+          break
+        case 'fulfilled':
+          if (
+            nextResult.status === 'error' ||
+            nextResult.data !== prevThenable.value
+          ) {
+            recreateThenable()
+          }
+          break
+        case 'rejected':
+          if (
+            nextResult.status !== 'error' ||
+            nextResult.error !== prevThenable.reason
+          ) {
+            recreateThenable()
+          }
+          break
+      }
+    }
+
     this.#currentResult = nextResult
 
     // Determine which callbacks to trigger
@@ -639,6 +697,7 @@ export class QueryObserver<
       return Object.keys(this.#currentResult).some((key) => {
         const typedKey = key as keyof QueryObserverResult
         const changed = this.#currentResult[typedKey] !== prevResult[typedKey]
+
         return changed && includedProps.has(typedKey)
       })
     }