Docgen: Update extraction of React docgen #33598

ndelangen · 2026-01-20T14:38:04Z

What I did

Noticed a bug in the gathering of react-docgen-data, we passed the containing-object data, instead of the data.

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

stories
unit tests
integration tests
end-to-end tests

Manual testing

Caution

This section is mandatory for all contributions. If you believe no manual test is necessary, please state so explicitly. Thanks!

Documentation

Add or update documentation reflecting your changes
If you are deprecating/removing a feature, make sure to update
MIGRATION.MD

Checklist for Maintainers

When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli-storybook/src/sandbox-templates.ts
Make sure this PR contains one of the labels below:
Available labels
- bug: Internal changes that fixes incorrect behavior.
- maintenance: User-facing maintenance tasks.
- dependencies: Upgrading (sometimes downgrading) dependencies.
- build: Internal-facing build tooling & test updates. Will not show up in release changelog.
- cleanup: Minor cleanup style change. Will not show up in release changelog.
- documentation: Documentation only changes. Will not show up in release changelog.
- feature request: Introducing a new feature.
- BREAKING CHANGE: Changes that break compatibility in some way with current major version.
- other: Changes that don't fit in the above categories.

🦋 Canary release

This pull request has been released as version 0.0.0-pr-33598-sha-c91e37ca. Try it out in a new sandbox by running npx storybook@0.0.0-pr-33598-sha-c91e37ca sandbox or in an existing project with npx storybook@0.0.0-pr-33598-sha-c91e37ca upgrade.

More information


Published version	`0.0.0-pr-33598-sha-c91e37ca`
Triggered by	@yannbf
Repository	storybookjs/storybook
Branch	`norbert/fix-js-docgen-data`
Commit	`c91e37ca`
Datetime	Tue Jan 20 15:00:09 UTC 2026 (`1768921209`)
Workflow run	21176214594

To request a new release of this pull request, mention the @storybookjs/core team.

core team members can create a new canary release here or locally with gh workflow run --repo storybookjs/storybook publish.yml --field pr=33598

Summary by CodeRabbit

Bug Fixes
- Corrected component documentation extraction so documentation data is sourced and interpreted reliably.
- Improved generation of array-type argument values with safer handling for empty or unspecified element types, reducing incorrect or unexpected argument outputs.

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

nx-cloud · 2026-01-20T14:38:55Z

View your CI Pipeline Execution ↗ for commit 2336b2e

Command	Status	Duration	Result
`nx run-many -t compile,check,knip,test,pretty-d...`	❌ Failed	9m 49s	View ↗

☁️ Nx Cloud last updated this comment at 2026-01-20 15:24:23 UTC

coderabbitai · 2026-01-20T14:41:56Z

📝 Walkthrough

Walkthrough

extractReactDocgenInfo now reads docgen.reactDocgen.data instead of docgen.reactDocgen; the dummy-value generator for SBType arrays treats sbType.value as an optional array, returning [] for empty/'other' and otherwise generating from the first element.

Changes

Cohort / File(s)	Summary
React Docgen Data Access `code/renderers/react/src/componentManifest/reactDocgen/extractReactDocgenInfo.ts`	Switched the payload passed to `extractArgTypes` from `docgen.reactDocgen` to `docgen.reactDocgen.data` in `extractArgTypesFromDocgen`.
Array Type Dummy Value Generation `code/core/src/core-server/utils/get-dummy-args-from-argtypes.ts`	`generateDummyValueFromSBType` now treats `sbType.value` as an optional `SBType[]`; returns `[]` if empty or first element is `'other'`, otherwise generates a dummy value from `sbType.value[0]`.
Tests Updated for SBType[] `code/core/src/core-server/utils/get-dummy-args-from-argtypes.test.ts`	Test inputs updated to pass array-structured `SBType` values (type-only import added); observable test behavior unchanged.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

Core: Improve story generation and args extraction #33395: Touches the same docgen-to-argTypes flow and SBType array handling; likely overlaps the same codepaths.
Core: Fix react-docgen-typescript support in story creation #33586: Modifies extractReactDocgenInfo's docgen payload handling in the same file.
Core: Fix import statement for react-docgen-typescript #33589: Coordinated changes affecting docgen payload shape and array-type dummy-value logic across the same modules.

✨ Finishing touches

📝 Generate docstrings

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

storybook-app-bot · 2026-01-20T14:47:47Z

Package Benchmarks

^{Commit: 2336b2e, ran on 20 January 2026 at 15:22:21 UTC}

The following packages have significant changes to their size or dependencies:

`@storybook/builder-webpack5`

	Before	After	Difference
Dependency count	192	192	0
Self size	75 KB	75 KB	🎉 -6 B 🎉
Dependency size	32.24 MB	32.25 MB	🚨 +11 KB 🚨
Bundle Size Analyzer	Link	Link

`storybook`

	Before	After	Difference
Dependency count	49	49	0
Self size	20.30 MB	20.32 MB	🚨 +21 KB 🚨
Dependency size	16.52 MB	16.52 MB	🎉 -4 B 🎉
Bundle Size Analyzer	Link	Link

`@storybook/ember`

	Before	After	Difference
Dependency count	196	196	0
Self size	15 KB	15 KB	🚨 +12 B 🚨
Dependency size	28.96 MB	28.97 MB	🚨 +11 KB 🚨
Bundle Size Analyzer	Link	Link

`@storybook/nextjs`

	Before	After	Difference
Dependency count	538	538	0
Self size	646 KB	646 KB	🚨 +110 B 🚨
Dependency size	59.22 MB	59.73 MB	🚨 +505 KB 🚨
Bundle Size Analyzer	Link	Link

`@storybook/nextjs-vite`

	Before	After	Difference
Dependency count	127	127	0
Self size	1.12 MB	1.12 MB	🚨 +14 B 🚨
Dependency size	21.82 MB	22.32 MB	🚨 +496 KB 🚨
Bundle Size Analyzer	Link	Link

`@storybook/react-native-web-vite`

	Before	After	Difference
Dependency count	159	159	0
Self size	30 KB	30 KB	🚨 +8 B 🚨
Dependency size	23.00 MB	23.61 MB	🚨 +610 KB 🚨
Bundle Size Analyzer	Link	Link

`@storybook/react-vite`

	Before	After	Difference
Dependency count	117	117	0
Self size	35 KB	35 KB	🎉 -8 B 🎉
Dependency size	19.62 MB	20.11 MB	🚨 +496 KB 🚨
Bundle Size Analyzer	Link	Link

`@storybook/react-webpack5`

	Before	After	Difference
Dependency count	278	278	0
Self size	24 KB	24 KB	🎉 -10 B 🎉
Dependency size	44.13 MB	44.64 MB	🚨 +505 KB 🚨
Bundle Size Analyzer	Link	Link

`@storybook/server-webpack5`

	Before	After	Difference
Dependency count	204	204	0
Self size	16 KB	16 KB	🎉 -10 B 🎉
Dependency size	33.49 MB	33.50 MB	🚨 +11 KB 🚨
Bundle Size Analyzer	Link	Link

`@storybook/cli`

	Before	After	Difference
Dependency count	183	183	0
Self size	775 KB	775 KB	🚨 +219 B 🚨
Dependency size	67.38 MB	67.47 MB	🚨 +92 KB 🚨
Bundle Size Analyzer	Link	Link

`@storybook/codemod`

	Before	After	Difference
Dependency count	176	176	0
Self size	30 KB	30 KB	🎉 -4 B 🎉
Dependency size	65.95 MB	66.05 MB	🚨 +92 KB 🚨
Bundle Size Analyzer	Link	Link

`create-storybook`

	Before	After	Difference
Dependency count	50	50	0
Self size	1000 KB	1000 KB	🎉 -6 B 🎉
Dependency size	36.82 MB	36.84 MB	🚨 +21 KB 🚨
Bundle Size Analyzer	node	node

`@storybook/preset-react-webpack`

	Before	After	Difference
Dependency count	170	170	0
Self size	18 KB	18 KB	🚨 +18 B 🚨
Dependency size	31.26 MB	31.28 MB	🚨 +11 KB 🚨
Bundle Size Analyzer	Link	Link

`@storybook/react`

	Before	After	Difference
Dependency count	57	57	0
Self size	732 KB	1.23 MB	🚨 +494 KB 🚨
Dependency size	12.94 MB	12.94 MB	🚨 +2 KB 🚨
Bundle Size Analyzer	Link	Link

…mmy value generation logic

storybook-bot · 2026-01-20T14:55:44Z

Failed to publish canary version of this pull request, triggered by @yannbf. See the failed workflow run at: https://github.com/storybookjs/storybook/actions/runs/21175957704

…argument generation logic

coderabbitai

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@code/core/src/core-server/utils/get-dummy-args-from-argtypes.ts`:
- Around line 229-236: In the 'array' branch handling SBType arrays, the guard
wrongly uses "v?.length < 1" which lets v undefined fallthrough and cause v[0]
access to throw; change the condition to check for missing/empty arrays first
(e.g. use "!v?.length" or an explicit "if (!v || v.length === 0)") so that when
sbType.value (v) is undefined or empty you return [] before checking v[0]?.name;
update the conditional in the case 'array' block surrounding
generateDummyValueFromSBType(v[0], propName, options) accordingly.

coderabbitai · 2026-01-20T15:02:13Z

code/core/src/core-server/utils/get-dummy-args-from-argtypes.ts

    case 'array': {
+      const v = sbType.value as unknown as SBType[];
+
      // If we don't know what the element is, be conservative and return empty.
-      if (sbType.value.name === 'other') {
+      if (v?.length < 1 || v[0]?.name === 'other') {
        return [];
      }
-      return [generateDummyValueFromSBType(sbType.value, propName, options)];
+      return [generateDummyValueFromSBType(v[0], propName, options)];


⚠️ Potential issue | 🟠 Major

Guard condition fails when v is undefined.

The condition v?.length < 1 doesn't protect against undefined values. When v is undefined:

v?.length evaluates to undefined

undefined < 1 is false (NaN comparison)

Code proceeds to v[0]?.name, which throws TypeError

Use !v?.length instead, which correctly handles both undefined/null and empty arrays.

Proposed fix

case 'array': { const v = sbType.value as unknown as SBType[]; // If we don't know what the element is, be conservative and return empty. - if (v?.length < 1 || v[0]?.name === 'other') { + if (!v?.length || v[0]?.name === 'other') { return []; } return [generateDummyValueFromSBType(v[0], propName, options)]; }

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change

case 'array': {

const v = sbType.value as unknown as SBType[];

// If we don't know what the element is, be conservative and return empty.

if (sbType.value.name === 'other') {

if (v?.length < 1 || v[0]?.name === 'other') {

return [];

}

return [generateDummyValueFromSBType(sbType.value, propName, options)];

return [generateDummyValueFromSBType(v[0], propName, options)];

case 'array': {

const v = sbType.value as unknown as SBType[];

// If we don't know what the element is, be conservative and return empty.

if (!v?.length || v[0]?.name === 'other') {

return [];

}

return [generateDummyValueFromSBType(v[0], propName, options)];

}

🤖 Prompt for AI Agents

In `@code/core/src/core-server/utils/get-dummy-args-from-argtypes.ts` around lines 229 - 236, In the 'array' branch handling SBType arrays, the guard wrongly uses "v?.length < 1" which lets v undefined fallthrough and cause v[0] access to throw; change the condition to check for missing/empty arrays first (e.g. use "!v?.length" or an explicit "if (!v || v.length === 0)") so that when sbType.value (v) is undefined or empty you return [] before checking v[0]?.name; update the conditional in the case 'array' block surrounding generateDummyValueFromSBType(v[0], propName, options) accordingly.

…correct, but the types are wrong, changing the type (we tried) breaks more things

Fix: Update extraction of React docgen info to use correct data property

ec6b251

ndelangen self-assigned this Jan 20, 2026

ndelangen added the ci:normal label Jan 20, 2026

ndelangen requested a review from yannbf January 20, 2026 14:38

ndelangen added bug docgen react labels Jan 20, 2026

ndelangen marked this pull request as ready for review January 20, 2026 14:38

Core: Update SBArrayType to support an array of SBType and improve du…

6b2b003

…mmy value generation logic

yannbf approved these changes Jan 20, 2026

View reviewed changes

Core: Refactor SBArrayType to hold a single SBType and enhance dummy …

c91e37c

…argument generation logic

coderabbitai bot reviewed Jan 20, 2026

View reviewed changes

fix test by ignoring typescript incorrect sbType value, the array IS …

2336b2e

…correct, but the types are wrong, changing the type (we tried) breaks more things

ndelangen merged commit c6a956d into next Jan 20, 2026
61 of 94 checks passed

ndelangen deleted the norbert/fix-js-docgen-data branch January 20, 2026 15:22

github-actions bot mentioned this pull request Jan 20, 2026

Release: Prerelease 10.2.0-beta.4 #33582

Merged

18 tasks

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Docgen: Update extraction of React docgen #33598

Docgen: Update extraction of React docgen #33598

Uh oh!

ndelangen commented Jan 20, 2026 •

edited by coderabbitai bot

Loading

nx-cloud bot commented Jan 20, 2026 •

edited

Loading

coderabbitai bot commented Jan 20, 2026 •

edited

Loading

Walkthrough

Changes

Estimated code review effort

Possibly related PRs

storybook-app-bot bot commented Jan 20, 2026 •

edited

Loading

storybook-bot commented Jan 20, 2026

coderabbitai bot left a comment

coderabbitai bot Jan 20, 2026

Uh oh!

Labels

4 participants

Uh oh!

Docgen: Update extraction of React docgen #33598

Docgen: Update extraction of React docgen #33598

Uh oh!

Conversation

ndelangen commented Jan 20, 2026 • edited by coderabbitai bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

What I did

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

Manual testing

Documentation

Checklist for Maintainers

🦋 Canary release

Summary by CodeRabbit

nx-cloud bot commented Jan 20, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

coderabbitai bot commented Jan 20, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Walkthrough

Changes

Estimated code review effort

Possibly related PRs

storybook-app-bot bot commented Jan 20, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Package Benchmarks

@storybook/builder-webpack5

storybook

@storybook/ember

@storybook/nextjs

@storybook/nextjs-vite

@storybook/react-native-web-vite

@storybook/react-vite

@storybook/react-webpack5

@storybook/server-webpack5

@storybook/cli

@storybook/codemod

create-storybook

@storybook/preset-react-webpack

@storybook/react

storybook-bot commented Jan 20, 2026

coderabbitai bot left a comment

Choose a reason for hiding this comment

coderabbitai bot Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

Labels

4 participants

ndelangen commented Jan 20, 2026 •

edited by coderabbitai bot

Loading

nx-cloud bot commented Jan 20, 2026 •

edited

Loading

coderabbitai bot commented Jan 20, 2026 •

edited

Loading

storybook-app-bot bot commented Jan 20, 2026 •

edited

Loading

`@storybook/builder-webpack5`

`storybook`

`@storybook/ember`

`@storybook/nextjs`

`@storybook/nextjs-vite`

`@storybook/react-native-web-vite`

`@storybook/react-vite`

`@storybook/react-webpack5`

`@storybook/server-webpack5`

`@storybook/cli`

`@storybook/codemod`

`create-storybook`

`@storybook/preset-react-webpack`

`@storybook/react`