fix: improve type inference for array of enums

[Newbie012]

Enhances type inference for arrays of enums in the TypeScript generation logic, ensuring that it correctly expands to the enum's members instead of defaulting to unknown[]. Additionally, adds testing guidelines for running tests in the project.

Summary by CodeRabbit

• Bug Fixes
  • Fixed type inference for arrays of enums—they now correctly expand to individual enum member types instead of being inferred as unknown[].

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[changeset-bot]

🦋 Changeset detected

Latest commit: 1dd9be2

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

This PR includes changesets to release 17 packages

Name	Type
@ts-safeql/eslint-plugin	Patch
@ts-safeql/generate	Patch
@ts-safeql-demos/basic-flat-config	Patch
@ts-safeql-demos/basic-migrations-raw	Patch
@ts-safeql-demos/basic-transform-type	Patch
@ts-safeql-demos/basic	Patch
@ts-safeql-demos/big-project	Patch
@ts-safeql-demos/config-file-flat-config	Patch
@ts-safeql-demos/from-config-file	Patch
@ts-safeql-demos/multi-connections	Patch
@ts-safeql-demos/playground	Patch
@ts-safeql-demos/postgresjs-custom-types	Patch
@ts-safeql-demos/postgresjs-demo	Patch
@ts-safeql-demos/vercel-postgres	Patch
@ts-safeql/shared	Patch
@ts-safeql/sql-ast	Patch
@ts-safeql/test-utils	Patch

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1 Skipped Deployment

Project	Deployment	Review	Updated (UTC)
safeql	Ignored	Preview	Dec 22, 2025 8:36am

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📥 Commits

Reviewing files that changed from the base of the PR and between 510cf76 and 1dd9be2.

📒 Files selected for processing (1)

• packages/generate/src/generate.ts

Walkthrough

The changes implement a fix for inferring array enum types during code generation. A new typelem field is added to the PostgreSQL type metadata structure, enum resolution helpers are introduced across the generate module, and a test validates that array enum columns correctly expand to union types of enum members.

Changes

Cohort / File(s)	Summary
Configuration & Testing Guidance .changeset/fancy-chefs-cough.md, .cursor/rules/testing.mdc	Adds changeset documenting bugfix for array enum inference; introduces testing guidance file with Vitest workflow and examples.
Type System & Enum Resolution packages/generate/src/generate.ts	Adds typelem field to PgTypeRow interface; updates SQL query to select typelem; introduces getEnumByOid helper; extends enum resolution to support array types by checking element type when direct OID lookup fails.
AST Description & Type Conversion packages/generate/src/ast-describe.ts	Refactors enum handling with pgType constant fetched once per operation; introduces getEnumByOid helper for safe enum lookup; adds valueAsEnum logic that prefers exact enum by OID or falls back to array enum resolution; integrates enum-based descriptions into main type resolution flow.
Test Coverage packages/generate/src/generate.test.ts	Adds test case "select array of enums" validating inference of my_enum[] columns expands to union of enum literal members.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~50 minutes

• packages/generate/src/generate.ts: Review the new typelem field addition to PgTypeRow, verify SQL query change is complete, and validate the two-stage enum resolution logic (direct OID lookup → array element fallback)
• packages/generate/src/ast-describe.ts: Examine the new helper functions getEnumByOid and valueAsEnum for correct null-safety and enum precedence; ensure non-enum paths remain unaffected
• Integration point: Confirm that typelem field flows correctly from SQL retrieval through both files and that the fallback logic preserves existing behavior for non-enum types

Poem

🐰 An array of enums, once shrouded in mystery,
Now sparkles with clarity through our history!
Typelem whispers its secrets so true,
Resolving each member to a union anew.
No more unknown[], just beauty displayed—
Type safety's gambit, perfectly played! ✨

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 (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix: improve type inference for array of enums' directly and clearly summarizes the main change: fixing type inference for array of enums to expand to enum members instead of unknown[].

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Actionable comments posted: 0

🧹 Nitpick comments (1)

packages/generate/src/generate.ts (1)

461-496: LGTM!

The enum resolution logic correctly implements the two-stage lookup:

1. Direct enum lookup by OID
2. Fallback to array element enum via typelem

The implementation is consistent with ast-describe.ts.

Consider extracting the getEnumByOid and valueAsEnum logic into a shared utility function to avoid duplication between generate.ts and ast-describe.ts. Both files implement nearly identical logic for enum resolution.

📜 Review details

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between ac7a1b7 and 510cf76.

📒 Files selected for processing (5)

• .changeset/fancy-chefs-cough.md
• .cursor/rules/testing.mdc
• packages/generate/src/ast-describe.ts
• packages/generate/src/generate.test.ts
• packages/generate/src/generate.ts

🔇 Additional comments (8)

.cursor/rules/testing.mdc (1)

1-29: LGTM!

The testing guidelines are clear and provide a useful reference for running Vitest tests in the monorepo structure. The step-by-step workflow and example command are helpful for developers.

.changeset/fancy-chefs-cough.md (1)

1-6: LGTM!

The changeset correctly identifies both affected packages and accurately describes the fix for array enum inference.

packages/generate/src/generate.test.ts (1)

2486-2510: LGTM!

The test case effectively validates the new array enum inference feature. The expected output structure correctly represents an array containing a union of the enum's string literal members, which aligns with the implementation changes in ast-describe.ts and generate.ts.

packages/generate/src/ast-describe.ts (3)

117-127: LGTM!

Good refactor to retrieve pgType early and use it for the type field. The optional chaining with fallback to "unknown" handles missing types gracefully.

---

140-180: LGTM!

The two-stage enum resolution logic is well-structured:

1. Direct enum lookup by OID
2. Fallback to array element enum when typelem is present and non-zero

The use of satisfies ASTDescribedColumnType ensures type safety for the array wrapper.

---

187-187: LGTM!

Consistent use of pgType?.name for the type field with proper fallback.

packages/generate/src/generate.ts (2)

627-631: LGTM!

The typelem field is correctly typed as number (PostgreSQL OID type). This field contains the element type OID for array types, which is essential for the array enum resolution.

---

635-638: LGTM!

The SQL query correctly fetches typelem from pg_type. This is a standard PostgreSQL catalog column that stores the OID of the element type for array types.