fix(form-core): fix fields being stale on array changes

[LeCarbonator]

Closes #1614
Closes #1561
Closes #1577
Closes #1289

Fixes:

• field.handleChange(undefined) no longer sets the value to the default value
• form.reset() and array methods no longer break controlled input when non-index keys are used
• field values in arrays no longer temporarily become undefined (breaking controlled -> uncontrolled -> controlled)

Todos:

• Test at workplace (known location where previous implementation crashed due to dnd)
• Test performance (what does the rerendering look like now?)
  • children callback
  • Form Composition
• Check other frameworks
  • Solid
  • Angular
  • Vue
  • Svelte
  • Lit

[nx-cloud]

View your CI Pipeline Execution ↗ for commit 4a489fa

Command	Status	Duration	Result
nx affected --targets=test:sherif,test:knip,tes...	✅ Succeeded	1m 13s	View ↗
nx run-many --target=build --exclude=examples/**	✅ Succeeded	32s	View ↗

---

☁️ Nx Cloud last updated this comment at 2025-11-24 10:11:17 UTC

[pkg-pr-new]

More templates

• @tanstack/form-example-angular-array
• @tanstack/form-example-angular-large-form
• @tanstack/form-example-angular-simple
• @tanstack/form-example-angular-standard-schema
• @tanstack/form-example-lit-array
• @tanstack/form-example-lit-simple
• @tanstack/form-example-lit-standard-schema
• @tanstack/form-example-lit-ui-libraries
• @tanstack/form-example-react-array
• @tanstack/form-example-react-compiler
• @tanstack/form-example-react-devtools
• @tanstack/form-example-react-dynamic
• @tanstack/field-errors-from-form-validators
• @tanstack/form-example-react-large-form
• @tanstack/form-example-react-next-server-actions
• @tanstack/form-example-react-query-integration
• @tanstack/form-example-remix
• @tanstack/form-example-react-simple
• @tanstack/form-example-react-standard-schema
• @tanstack/form-example-react-tanstack-start
• @tanstack/form-example-react-ui-libraries
• @tanstack/form-example-solid-array
• @tanstack/form-example-solid-devtools
• @tanstack/form-example-solid-large-form
• @tanstack/form-example-solid-simple
• @tanstack/form-example-solid-standard-schema
• @tanstack/form-example-svelte-array
• @tanstack/form-example-svelte-simple
• @tanstack/form-example-svelte-standard-schema
• @tanstack/form-example-vue-array
• @tanstack/form-example-vue-simple
• @tanstack/form-example-vue-standard-schema

@tanstack/angular-form

npm i https://pkg.pr.new/@tanstack/angular-form@1729

@tanstack/form-core

npm i https://pkg.pr.new/@tanstack/form-core@1729

@tanstack/form-devtools

npm i https://pkg.pr.new/@tanstack/form-devtools@1729

@tanstack/lit-form

npm i https://pkg.pr.new/@tanstack/lit-form@1729

@tanstack/react-form

npm i https://pkg.pr.new/@tanstack/react-form@1729

@tanstack/react-form-devtools

npm i https://pkg.pr.new/@tanstack/react-form-devtools@1729

@tanstack/react-form-nextjs

npm i https://pkg.pr.new/@tanstack/react-form-nextjs@1729

@tanstack/react-form-remix

npm i https://pkg.pr.new/@tanstack/react-form-remix@1729

@tanstack/react-form-start

npm i https://pkg.pr.new/@tanstack/react-form-start@1729

@tanstack/solid-form

npm i https://pkg.pr.new/@tanstack/solid-form@1729

@tanstack/solid-form-devtools

npm i https://pkg.pr.new/@tanstack/solid-form-devtools@1729

@tanstack/svelte-form

npm i https://pkg.pr.new/@tanstack/svelte-form@1729

@tanstack/vue-form

npm i https://pkg.pr.new/@tanstack/vue-form@1729

commit: 4a489fa

[codecov]

Codecov Report

❌ Patch coverage is 97.70115% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.23%. Comparing base (6892ed0) to head (4a489fa).
⚠️ Report is 59 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/form-core/src/FieldApi.ts	94.73%	1 Missing ⚠️
packages/form-core/src/metaHelper.ts	98.21%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1729      +/-   ##
==========================================
- Coverage   90.35%   90.23%   -0.13%     
==========================================
  Files          38       41       +3     
  Lines        1752     1853     +101     
  Branches      444      469      +25     
==========================================
+ Hits         1583     1672      +89     
- Misses        149      162      +13     
+ Partials       20       19       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[LeCarbonator]

Notes to self:

Swapping, deletion and basic reset seems to work. However, there's conflicts with the reset that need further investigating.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 4a489fa

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

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

[LeCarbonator]

form.reset() still has the issue if the array field's size changes.

swapValues, moveValues and removeValue seem to be fixed.

[LeCarbonator]

form.reset() and array methods are all fixed.

Todos:

• Test at workplace (known location where previous implementation crashed due to dnd)
• Test performance (what does the rerendering look like now?)
  • children callback
  • Form Composition
• Check other frameworks
  • Solid
  • Angular
  • Vue
  • Svelte
  • Lit

[LeCarbonator]

Solid appears to be struggling with this implementation still. I'll look into what can be done to fix it.

[LeCarbonator]

Looks like svelte has a problem when using a keyed list

[LeCarbonator]

Arrays look to be fixed, at least confirmed for React.

However, it looks like defaultValue and defaultMeta have been broken in the process. This might also highlight stale unit tests, so I'll have to go through that thoroughly.

[harry-whorlow]

pr works in local code base, and fixes array bug.

[LeCarbonator]

I'll add a solidjs test later. After that, it's good to merge.

[willbowdler-cc]

Please merge this 🙏