fix(openapi): only filter undefined from array nodes

[kricsleo]

🔗 Linked issue

resolves #3892

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[vercel]

@kricsleo is attempting to deploy a commit to the Nitro Team on Vercel.

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[coderabbitai]

📝 Walkthrough

Walkthrough

Fixes a bug where falsy enum values (like 0 and empty strings) were excluded from OpenAPI definitions. Modifies the array filtering logic in the route metadata plugin to remove only undefined values instead of all falsy values, while updating test fixtures and snapshots to verify the fix.

Changes

Cohort / File(s)	Change Summary
Core Fix src/build/plugins/route-meta.ts	Changed ArrayExpression filter from .filter(Boolean) to .filter((obj) => obj !== undefined) to preserve falsy values (0, false, empty string, null) in enum definitions while removing only undefined results.
Test Updates test/fixture/server/routes/api/meta/test.ts, test/presets/nitro-dev.test.ts	Added new query parameter "val" with integer type and enum [0, 1] to test fixture and updated corresponding OpenAPI snapshot to verify falsy enum values are now included.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

• Focus on the logic change in route-meta.ts to confirm the filter correctly excludes only undefined while preserving other falsy values
• Verify test fixture accurately demonstrates the fix for falsy enum values (specifically value 0)
• Confirm snapshot changes reflect the expected OpenAPI output with the new parameter

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title follows conventional commits format with 'fix' type and a clear, descriptive description of the change.
Description check	✅ Passed	The description provides a linked issue reference and identifies the change type as a bug fix, clearly relating to the code modifications.
Linked Issues check	✅ Passed	The code changes directly address issue #3892 by modifying the array filtering logic to preserve falsy values like 0 and empty strings in OpenAPI enum definitions.
Out of Scope Changes check	✅ Passed	All changes focus on fixing the OpenAPI enum filtering issue; the test updates properly document the new 'val' parameter behavior and are within scope.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

test/fixture/server/routes/api/meta/test.ts (1)

7-14: Good test coverage for the falsy value bug, consider expanding.

The new parameter with enum: [0, 1] effectively tests that the falsy value 0 is now correctly preserved in the OpenAPI output, directly addressing the reported issue.

Consider adding test coverage for other falsy values like empty strings (""), false, or edge cases to ensure comprehensive validation of the fix.

🔎 Example: Additional test parameter with empty string enum

{
  in: "query",
  name: "status",
  schema: { type: "string", enum: ["", "active", "inactive"] },
}

📜 Review details

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 0f3740d and e9d1b7c.

📒 Files selected for processing (3)

• src/build/plugins/route-meta.ts
• test/fixture/server/routes/api/meta/test.ts
• test/presets/nitro-dev.test.ts

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (4)

• GitHub Check: tests-rollup (windows-latest)
• GitHub Check: tests-rollup (ubuntu-latest)
• GitHub Check: tests-rolldown (windows-latest)
• GitHub Check: tests-rolldown (ubuntu-latest)

🔇 Additional comments (2)

test/presets/nitro-dev.test.ts (1)

48-58: LGTM! Snapshot correctly reflects the fix.

The updated snapshot confirms that the falsy value 0 now correctly appears in the OpenAPI enum, validating that the fix works end-to-end from route metadata definition to OpenAPI output.

src/build/plugins/route-meta.ts (1)

106-108: The fix correctly preserves null values in arrays—this is intentional.

The change from .filter(Boolean) to .filter((obj) => obj !== undefined) is the correct fix. According to commit e9d1b7c, this was specifically designed to "only filter undefined from array nodes," preserving legitimate falsy values like 0, "", false, and null that may appear in route metadata. This prevents legitimate data from being lost during OpenAPI metadata extraction.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/nitrojs/nitro@3894

commit: e9d1b7c

[pi0]

Thanks!