Preserve empty string array values in submissions by morgan-coded · Pull Request #1233 · edmundhung/conform

morgan-coded · 2026-06-09T15:03:47Z

parseWithZod could drop an empty string inside an array field because that value was treated like it was absent. That can lose or shift array entries in the parsed submission payload.

This narrows the presence check so only undefined is treated as missing. I checked it with the focused conform-dom submission test, changed-file oxlint, changed-file oxfmt --check, and git diff --check.

Closes #839

Generated Summary

Changes

Modified the presence check in packages/conform-dom/submission.ts to preserve empty string values in array fields. The reducer now treats only undefined as missing (previously treated any falsy value as missing):

// Before: !prev (treats empty string as missing)
// After: prev === undefined (only undefined is missing)

This ensures empty string elements in arrays are not dropped during form submission parsing, maintaining correct array indices and element ordering.

Additional updates

Added Changesets entry documenting the behavior change
Added test verifying empty strings are preserved within array fields during parsing

changeset-bot · 2026-06-09T15:04:01Z

🦋 Changeset detected

Latest commit: b51f716

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

This PR includes changesets to release 5 packages

Name	Type
@conform-to/dom	Patch
@conform-to/react	Patch
@conform-to/valibot	Patch
@conform-to/yup	Patch
@conform-to/zod	Patch

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coderabbitai · 2026-06-09T15:04:02Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Run ID: 54eda280-b290-42d6-9276-6d54a560f7cd

📥 Commits

Reviewing files that changed from the base of the PR and between c7f8874 and b51f716.

📒 Files selected for processing (3)

.changeset/fix-array-empty-string.md
packages/conform-dom/submission.ts
packages/conform-dom/tests/submission.test.ts

📜 Recent review details

🧰 Additional context used

🪛 markdownlint-cli2 (0.22.1)

.changeset/fix-array-empty-string.md

[warning] 5-5: First line in a file should be a top-level heading

(MD041, first-line-heading, first-line-h1)

🔇 Additional comments (3)

.changeset/fix-array-empty-string.md (1)

1-5: LGTM!

packages/conform-dom/submission.ts (1)

104-110: LGTM!

packages/conform-dom/tests/submission.test.ts (1)

285-309: LGTM!

📝 Walkthrough

Walkthrough

This PR fixes a bug in the form submission payload builder where empty strings and other falsy-but-valid values (0, false) were being lost in array fields. The fix changes the value-merging logic to only treat undefined as "no prior value," and includes a test case verifying empty strings are preserved.

Changes

Empty string preservation in array fields

Layer / File(s)	Summary
Fix falsy value handling in submission context `.changeset/fix-array-empty-string.md`, `packages/conform-dom/submission.ts`	The `getSubmissionContext` reducer now checks `prev === undefined` instead of `!prev` when determining whether to overwrite or accumulate array field values, so empty strings and other falsy values are no longer dropped. Changeset documents this as a patch release for `@conform-to/dom`.
Test empty string preservation in arrays `packages/conform-dom/tests/submission.test.ts`	New test case submits array entries with empty strings interspersed and verifies the parsed payload retains all entries in order.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐰 A string so empty, once was lost,
Within the arrays, falsy crossed,
But now undefined marks the way,
And empty values get to stay! ✨

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and accurately describes the main change: preserving empty string values in array submissions, which is the core focus of the PR.
Linked Issues check	✅ Passed	The changes fully address issue `#839` by narrowing the presence check from falsy values to only `undefined`, ensuring empty strings are preserved in array fields during submission parsing.
Out of Scope Changes check	✅ Passed	All changes are directly related to fixing the empty string array preservation issue; the changeset entry, submission logic fix, and test are all in scope and focused on issue `#839`.

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Copilot

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR fixes how submission payloads are constructed for repeated (array) fields so that empty string values are preserved instead of being treated as “missing”.

Changes:

Adjust payload aggregation logic to treat only undefined as “no previous value” (preserving falsy values like '').
Add a regression test covering empty strings within array fields.
Add a changeset describing the patch fix for @conform-to/dom.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
packages/conform-dom/tests/submission.test.ts	Adds a test ensuring `parse()` preserves empty strings in repeated fields.
packages/conform-dom/submission.ts	Fixes array-field accumulation by not treating `''` as an absent previous value.
.changeset/fix-array-empty-string.md	Documents the patch release and behavior change.

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pkg-pr-new · 2026-06-09T15:05:09Z

More templates

@conform-to/dom

npm i https://pkg.pr.new/@conform-to/dom@1233

@conform-to/react

npm i https://pkg.pr.new/@conform-to/react@1233

@conform-to/valibot

npm i https://pkg.pr.new/@conform-to/valibot@1233

@conform-to/validitystate

npm i https://pkg.pr.new/@conform-to/validitystate@1233

@conform-to/yup

npm i https://pkg.pr.new/@conform-to/yup@1233

@conform-to/zod

npm i https://pkg.pr.new/@conform-to/zod@1233

commit: b51f716

edmundhung

Thanks!

Preserve empty strings in array submissions

b51f716

Copilot AI review requested due to automatic review settings June 9, 2026 15:03

Copilot AI reviewed Jun 9, 2026

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Comment thread packages/conform-dom/submission.ts

coderabbitai Bot approved these changes Jun 9, 2026

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edmundhung approved these changes Jun 14, 2026

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edmundhung merged commit af2582e into edmundhung:main Jun 14, 2026
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Preserve empty string array values in submissions#1233

Preserve empty string array values in submissions#1233
edmundhung merged 1 commit into
edmundhung:mainfrom
morgan-coded:fix/839-array-empty-string

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morgan-coded commented Jun 9, 2026 •

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