fix(query-core): ensure onMutate runs synchronously when cache config is undefined (#8724) #10066

xxziiko · 2026-01-22T14:50:30Z

🎯 Changes

onMutate never actually runs synchronously #8724

Previously, mutationCache.config.onMutate was always awaited using optional chaining (await this.#mutationCache.config.onMutate?.()), which caused unnecessary async behavior even when the callback was undefined.

Changed to conditional check: only await when onMutate is actually defined
Added regression test to verify synchronous execution when cache config is not provided

✅ Checklist

I have followed the steps in the Contributing guide.
I have tested this code locally with pnpm run test:pr.

🚀 Release Impact

This change affects published code, and I have generated a changeset.
This change is docs/CI/dev-only (no release).

Summary by CodeRabbit

Bug Fixes
- Corrected onMutate callback execution to run synchronously when cache-level configuration is undefined.
Tests
- Added test coverage for synchronous callback behavior in mutation operations.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

… is undefined Fixes TanStack#8724

changeset-bot · 2026-01-22T14:50:35Z

🦋 Changeset detected

Latest commit: 1e71dcb

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 19 packages

Name	Type
@tanstack/query-core	Patch
@tanstack/angular-query-experimental	Patch
@tanstack/query-async-storage-persister	Patch
@tanstack/query-broadcast-client-experimental	Patch
@tanstack/query-persist-client-core	Patch
@tanstack/query-sync-storage-persister	Patch
@tanstack/react-query	Patch
@tanstack/solid-query	Patch
@tanstack/svelte-query	Patch
@tanstack/vue-query	Patch
@tanstack/angular-query-persist-client	Patch
@tanstack/react-query-persist-client	Patch
@tanstack/solid-query-persist-client	Patch
@tanstack/svelte-query-persist-client	Patch
@tanstack/react-query-devtools	Patch
@tanstack/react-query-next-experimental	Patch
@tanstack/solid-query-devtools	Patch
@tanstack/svelte-query-devtools	Patch
@tanstack/vue-query-devtools	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

coderabbitai · 2026-01-22T14:50:59Z

📝 Walkthrough

Walkthrough

This PR patches TanStack Query core to ensure the onMutate callback executes synchronously when mutationCache.config.onMutate is undefined. The fix replaces optional chaining with an explicit null check before awaiting, preventing unnecessary async wrapping when no cache-level onMutate handler exists.

Changes

Cohort / File(s)	Summary
Changeset Documentation `.changeset/giant-apples-wear.md`	Patch version bump documenting the onMutate synchronous execution fix
Test Coverage `packages/query-core/src/__tests__/mutationCache.test.tsx`	New test verifying onMutate executes synchronously when cache-level onMutate is not defined
Core Logic `packages/query-core/src/mutation.ts`	Changed optional chaining call to explicit presence check before awaiting onMutate, enabling synchronous execution when cache-level handler is absent

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

fix(types): onMutateResult is always defined in onSuccess callback #9677 — Modifies mutation lifecycle callback invocation patterns in the same source file
fix(chore): report errors of useMutation callbacks asynchronously #9676 — Changes mutation error handling and callback invocation logic in mutation.ts

Suggested labels

package: query-core

Suggested reviewers

TkDodo

Poem

🐰 A hop and a skip, the callback runs fast,
No waiting around when cache-config's not vast,
Synchronous now when undefined's the way,
Mutations proceed without delay—hooray!

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely summarizes the main fix: ensuring onMutate runs synchronously when cache config is undefined, directly matching the core change in mutation.ts and the test additions.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description check	✅ Passed	The pull request description follows the template structure with all required sections completed: Changes describe the fix with context, Checklist items are checked, and Release Impact is addressed with a changeset.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

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nx-cloud · 2026-01-22T14:51:03Z

🤖 Nx Cloud AI Fix Eligible

An automatically generated fix could have helped fix failing tasks for this run, but Self-healing CI is disabled for this workspace. Visit workspace settings to enable it and get automatic fixes in future runs.

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View your CI Pipeline Execution ↗ for commit 1e71dcb

Command	Status	Duration	Result
`nx affected --targets=test:sherif,test:knip,tes...`	❌ Failed	4m 17s	View ↗
`nx run-many --target=build --exclude=examples/*...`	✅ Succeeded	2s	View ↗

☁️ Nx Cloud last updated this comment at 2026-01-22 14:55:51 UTC

pkg-pr-new · 2026-01-22T14:51:57Z

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@tanstack/query-async-storage-persister

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@tanstack/query-broadcast-client-experimental

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@tanstack/query-core

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@tanstack/query-devtools

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commit: 1e71dcb

xxziiko added 2 commits January 22, 2026 21:37

chore: add changeset for onMutate sync fix

060bd43

fix(query-core): ensure onMutate runs synchronously when cache config…

1e71dcb

… is undefined Fixes TanStack#8724

github-actions bot added the package: query-core label Jan 22, 2026

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fix(query-core): ensure onMutate runs synchronously when cache config is undefined (#8724) #10066

fix(query-core): ensure onMutate runs synchronously when cache config is undefined (#8724) #10066

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