[v2] Fix: Keep ArrayField in sync after array replacement by scttcper · Pull Request #2356 · TanStack/form

scttcper · 2026-08-24T06:09:51Z

ArrayField only reacts to array length and _arrayVersion, so replacing an array with a different array of the same length updated form state without rerendering the array container. UI rendered from the array could stay stale while submission used the new values.

This bumps _arrayVersion for direct same-length replacements. Array helpers now rely on length changes or this shared behavior instead of manually updating the version, while nested field updates still avoid rerendering the parent ArrayField.

Summary by CodeRabbit

Bug Fixes
- Array fields now update reliably when replaced with a new array of the same length.
- Array components rerender when their array value changes, while avoiding unnecessary rerenders for nested field updates.
- Swapping, moving, and clearing array items now maintain consistent field updates.
Tests
- Added coverage for array replacement through direct values and updater functions, nested updates, and array helper operations.
- Added coverage confirming correct rerender behavior for array fields.

Replacing an array with another array of the same length updated form state without rerendering ArrayField. Bump the shared array version for direct replacements while keeping nested field updates isolated. Co-Authored-By: OpenAI Codex <noreply@openai.com>

coderabbitai · 2026-08-24T06:09:58Z

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packages/form-core/src/FormApi/FormApi.lib.ts

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📝 Walkthrough

Walkthrough

The change centralizes _arrayVersion updates in setFieldValue, removes duplicate updates from array helpers, and adds core and React tests for replacement, nested updates, helper operations, and ArrayField rerender behavior.

Changes

Array version tracking

Layer / File(s)	Summary
Centralize array-version updates `packages/form-core/src/FormApi/FormApi.lib.ts`, `packages/form-core/src/FormApi/array-methods.lib.ts`	`setFieldValue` resolves updater values before writing them and increments `_arrayVersion` for same-length array replacements. Array helpers no longer increment the metadata directly.
Validate array version behavior `packages/form-core/tests/FormApi/field-state.spec.ts`, `packages/react-form/tests/FormField.spec.tsx`	Tests cover direct and updater replacements, nested field updates, array helpers, and `ArrayField` rerender behavior.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Suggested reviewers: lecarbonator

Merge Risk: ⚪ Minimal · up to 17d23

Array replacements and nested updates retain the intended rendering behavior, so the change is ready to merge after normal checks.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description explains the code change and its motivation, but it does not use the required Changes, Checklist, or Release Impact sections. It also does not confirm the required local tests or chang…	Update the description to include the required ## 🎯 Changes, ## ✅ Checklist, and ## 🚀 Release Impact sections. Complete the checklist items and state whether a changeset is required or whether the change is docs/CI/dev-only.
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the primary change: keeping ArrayField synchronized after same-length array replacement.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Explanation

The description explains the code change and its motivation, but it does not use the required Changes, Checklist, or Release Impact sections. It also does not confirm the required local tests or changeset status.

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nx-cloud · 2026-08-27T10:21:04Z

View your CI Pipeline Execution ↗ for commit 17d23c9

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☁️ Nx Cloud last updated this comment at 2026-09-14 11:51:19 UTC

LeCarbonator

Noticed a small correctness bug, but apart from that, looks good! It might change a bit in the future to make the work of the adapters a bit easier, but that's not a concern atm. Thanks for the fix!

pkg-pr-new · 2026-09-14T11:47:32Z

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commit: 17d23c9

codecov-commenter · 2026-09-14T11:51:58Z

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scttcper commented Aug 24, 2026

View reviewed changes

Comment thread packages/react-form/tests/FormField.spec.tsx

scttcper marked this pull request as ready for review August 24, 2026 15:20

ci: apply automated fixes and generate docs

4f0849d

LeCarbonator approved these changes Sep 14, 2026

View reviewed changes

Comment thread packages/form-core/src/FormApi/FormApi.lib.ts Outdated

Update packages/form-core/src/FormApi/FormApi.lib.ts

17d23c9

LeCarbonator merged commit 6e5b809 into TanStack:alpha Sep 14, 2026
9 checks passed

scttcper deleted the scttcper/arrayfield-sync branch September 14, 2026 15:04

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[v2] Fix: Keep ArrayField in sync after array replacement - #2356

[v2] Fix: Keep ArrayField in sync after array replacement#2356
LeCarbonator merged 3 commits into
TanStack:alphafrom
scttcper:scttcper/arrayfield-sync

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scttcper commented Aug 24, 2026 •

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