feat: add notifyOnStatusChange flag

docs/src/pages/docs/api.md

@@ -7,40 +7,41 @@ title: API Reference
 
 ```js
 const {
-  status,
-  isIdle,
-  isLoading,
-  isSuccess,
-  isError,
+  clear,
   data,
   error,
-  isStale,
-  isFetching,
   failureCount,
+  isError,
+  isFetching,
+  isIdle,
+  isLoading,
+  isStale,
+  isSuccess,
   refetch,
-  clear,
+  status,
 } = useQuery(queryKey, queryFn?, {
-  suspense,
-  queryKeySerializerFn,
-  enabled,
-  retry,
-  retryDelay,
-  staleTime,
   cacheTime,
+  enabled,
+  initialData,
+  initialStale,
+  isDataEqual,
   keepPreviousData,
-  refetchOnWindowFocus,
-  refetchOnReconnect,
+  notifyOnStatusChange,
+  onError,
+  onSettled,
+  onSuccess,
+  queryFnParamsFilter,
+  queryKeySerializerFn,
   refetchInterval,
   refetchIntervalInBackground,
-  queryFnParamsFilter,
   refetchOnMount,
+  refetchOnReconnect,
+  refetchOnWindowFocus,
+  retry,
+  retryDelay,
+  staleTime,
   structuralSharing,
-  isDataEqual,
-  onError,
-  onSuccess,
-  onSettled,
-  initialData,
-  initialStale,
+  suspense,
   useErrorBoundary,
 })
 
@@ -96,6 +97,11 @@ const queryInfo = useQuery({
 - `refetchOnReconnect: Boolean`
   - Optional
   - Set this to `true` or `false` to enable/disable automatic refetching on reconnect for this query.
+- `notifyOnStatusChange: Boolean`
+  - Optional
+  - Whether a change to the query status should re-render a component.
+  - If set to `false`, the component will only re-render when the actual `data` or `error` changes.
+  - Defaults to `true`.
 - `onSuccess: Function(data) => data`
   - Optional
   - This function will fire any time the query successfully fetches new data.

src/core/config.ts

@@ -58,6 +58,7 @@ export const DEFAULT_CONFIG: ReactQueryConfig = {
     refetchOnWindowFocus: true,
     refetchOnReconnect: true,
     refetchOnMount: true,
+    notifyOnStatusChange: true,
     structuralSharing: true,
   },
 }

src/core/query.ts

@@ -469,7 +469,7 @@ export class Query<TResult, TError> {
     const config = this.config
 
     // Check if there is a query function
-    if (!config.queryFn) {
+    if (typeof config.queryFn !== 'function') {
       return
     }
 

src/core/queryCache.ts

@@ -313,7 +313,6 @@ export class QueryCache {
       if (options?.throwOnError) {
         throw error
       }
-      return
     } finally {
       if (query) {
         // When prefetching, no observer is tied to the query,

src/core/queryObserver.ts

@@ -157,39 +157,32 @@ export class QueryObserver<TResult, TError> {
 
   private createResult(): QueryResult<TResult, TError> {
     const { currentQuery, previousResult, config } = this
-
-    const {
-      canFetchMore,
-      error,
-      failureCount,
-      isFetched,
-      isFetching,
-      isFetchingMore,
-      isLoading,
-      isStale,
-    } = currentQuery.state
-
-    let { data, status, updatedAt } = currentQuery.state
+    const { state } = currentQuery
+    let { data, status, updatedAt } = state
 
     // Keep previous data if needed
-    if (config.keepPreviousData && isLoading && previousResult?.isSuccess) {
+    if (
+      config.keepPreviousData &&
+      state.isLoading &&
+      previousResult?.isSuccess
+    ) {
       data = previousResult.data
       updatedAt = previousResult.updatedAt
       status = previousResult.status
     }
 
     return {
       ...getStatusProps(status),
-      canFetchMore,
+      canFetchMore: state.canFetchMore,
       clear: this.clear,
       data,
-      error,
-      failureCount,
+      error: state.error,
+      failureCount: state.failureCount,
       fetchMore: this.fetchMore,
-      isFetched,
-      isFetching,
-      isFetchingMore,
-      isStale,
+      isFetched: state.isFetched,
+      isFetching: state.isFetching,
+      isFetchingMore: state.isFetchingMore,
+      isStale: state.isStale,
       query: currentQuery,
       refetch: this.refetch,
       updatedAt,
@@ -229,20 +222,35 @@ export class QueryObserver<TResult, TError> {
     _state: QueryState<TResult, TError>,
     action: Action<TResult, TError>
   ): void {
-    this.currentResult = this.createResult()
+    const { config } = this
 
-    const { data, error, isSuccess, isError } = this.currentResult
+    // Store current result and get new result
+    const prevResult = this.currentResult
+    this.currentResult = this.createResult()
+    const result = this.currentResult
 
-    if (action.type === 'Success' && isSuccess) {
-      this.config.onSuccess?.(data!)
-      this.config.onSettled?.(data!, null)
+    // We need to check the action because the state could have
+    // transitioned from success to success in case of `setQueryData`.
+    if (action.type === 'Success' && result.isSuccess) {
+      config.onSuccess?.(result.data!)
+      config.onSettled?.(result.data!, null)
       this.updateRefetchInterval()
-    } else if (action.type === 'Error' && isError) {
-      this.config.onError?.(error!)
-      this.config.onSettled?.(undefined, error!)
+    } else if (action.type === 'Error' && result.isError) {
+      config.onError?.(result.error!)
+      config.onSettled?.(undefined, result.error!)
       this.updateRefetchInterval()
     }
 
-    this.updateListener?.(this.currentResult)
+    // Decide if we need to notify the listener
+    const notify =
+      // Always notify on data or error change
+      result.data !== prevResult.data ||
+      result.error !== prevResult.error ||
+      // Maybe notify on other changes
+      config.notifyOnStatusChange
+
+    if (notify) {
+      this.updateListener?.(result)
+    }
   }
 }

src/core/types.ts

@@ -105,6 +105,12 @@ export interface QueryObserverConfig<
    * Defaults to `true`.
    */
   refetchOnMount?: boolean
+  /**
+   * Whether a change to the query status should re-render a component.
+   * If set to `false`, the component will only re-render when the actual `data` or `error` changes.
+   * Defaults to `true`.
+   */
+  notifyOnStatusChange?: boolean
   /**
    * This callback will fire any time the query successfully fetches new data.
    */

src/react/tests/useInfiniteQuery.test.tsx

@@ -60,7 +60,7 @@ describe('useInfiniteQuery', () => {
     await waitFor(() => rendered.getByText('Status: success'))
 
     expect(states[0]).toEqual({
-      canFetchmore: undefined,
+      canFetchMore: undefined,
       clear: expect.any(Function),
       data: undefined,
       error: null,

src/react/tests/useQuery.test.tsx

@@ -461,6 +461,111 @@ describe('useQuery', () => {
     })
   })
 
+  it('should re-render when a query becomes stale', async () => {
+    const key = queryKey()
+    const states: QueryResult<string>[] = []
+
+    function Page() {
+      const state = useQuery(key, () => 'test', {
+        staleTime: 50,
+      })
+      states.push(state)
+      return null
+    }
+
+    render(<Page />)
+
+    await waitFor(() => expect(states.length).toBe(3))
+
+    expect(states[0]).toMatchObject({
+      isStale: true,
+    })
+    expect(states[1]).toMatchObject({
+      isStale: false,
+    })
+    expect(states[2]).toMatchObject({
+      isStale: true,
+    })
+  })
+
+  it('should not re-render when a query status changes and notifyOnStatusChange is false', async () => {
+    const key = queryKey()
+
+    let count = 0
+    const fn = () => sleep(10).then(() => count++)
+
+    const states1: QueryResult<number>[] = []
+    const states2: QueryResult<number>[] = []
+
+    function FirstCounter() {
+      const state = useQuery(key, fn, {
+        notifyOnStatusChange: false,
+      })
+      states1.push(state)
+      return null
+    }
+
+    function SecondCounter() {
+      const state = useQuery(key, fn)
+      states2.push(state)
+      return null
+    }
+
+    function Footer() {
+      const [showCounter, setShowCounter] = React.useState(false)
+
+      React.useEffect(() => {
+        setTimeout(() => {
+          setShowCounter(true)
+        }, 20)
+      }, [])
+
+      return <div>{showCounter && <SecondCounter />}</div>
+    }
+
+    function Page() {
+      return (
+        <div>
+          <FirstCounter />
+          <Footer />
+        </div>
+      )
+    }
+
+    render(<Page />)
+
+    await waitFor(() => expect(states1[2]?.data).toBe(1))
+
+    expect(states1.length).toBe(3)
+
+    expect(states1[0]).toMatchObject({
+      status: 'loading',
+      isFetching: true,
+    })
+    expect(states1[1]).toMatchObject({
+      status: 'success',
+      isFetching: false,
+    })
+    expect(states1[2]).toMatchObject({
+      status: 'success',
+      isFetching: false,
+    })
+
+    expect(states2.length).toBe(3)
+    expect(states2[0]).toMatchObject({
+      status: 'success',
+      isFetching: false,
+    })
+    expect(states2[1]).toMatchObject({
+      status: 'success',
+      isFetching: true,
+    })
+    expect(states2[2]).toMatchObject({
+      status: 'success',
+      isFetching: false,
+    })
+  })
+
   // See https://github.com/tannerlinsley/react-query/issues/137
   it('should not override initial data in dependent queries', async () => {
     const key1 = queryKey()

src/react/tests/utils.tsx

@@ -1,3 +1,5 @@
+import { waitFor } from '@testing-library/react'
+
 let queryKeyCount = 0
 
 export function mockVisibilityState(value: string) {
@@ -31,6 +33,15 @@ export function sleep(timeout: number): Promise<void> {
   })
 }
 
+export function waitForMs(ms: number) {
+  const end = Date.now() + ms
+  return waitFor(() => {
+    if (Date.now() < end) {
+      throw new Error('Time not elapsed yet')
+    }
+  })
+}
+
 /**
  * Checks that `T` is of type `U`.
  */

src/react/useMutation.ts

@@ -172,8 +172,6 @@ export function useMutation<
         if (mutateConfig.throwOnError ?? config.throwOnError) {
           throw error
         }
-
-        return
       }
     },
     [dispatch, getConfig, getMutationFn]

tsconfig.json

@@ -6,7 +6,7 @@
     "target": "es5",
     "noEmit": true,
     "noImplicitAny": true,
-    "noImplicitReturns": true,
+    "noImplicitReturns": false,
     "noImplicitThis": true,
     "noUnusedLocals": true,
     "noUnusedParameters": true,