factory methods: discriminator aliases and missing parent properties - fix

[mironbalcerzak]

Problem

OpenAPI specifications defining polymorphic interfaces often use a combiner (oneOf/anyOf/allOf) alongside the parent schema's own properties.
However, Orval's factory generator treated combiners and properties as mutually exclusive.
When a combiner was found, the generator returned early and completely ignored the parent's own properties.

Relates to: #3523

Result of the bad code

The generated parent factory simply returned the variant's factory output, which lacked the parent's required properties.
This caused TypeScript compiler errors (e.g., TS2322: Type 'Variant' is not assignable to type 'Variant & { parentProp: string }') when trying to assign the factory output to the generated intersection type.

Example OpenAPI Spec causing the issue

openapi: 3.1.0
components:
  schemas:
    General:
      type: object
      oneOf:
        - $ref: '#/components/schemas/Specific'
      properties:
        responseType:
          type: string
      required:
        - responseType
    Specific:
      type: object
      properties:
        question:
          type: string

How we fixed it

Refactored buildPayload in packages/core/src/generators/factory.ts to no longer treat combiners and properties as mutually exclusive.
The logic now collects payloads from both the combiner and the parent properties into an array, and combines them using Object.assign({}, ...payloads).
This ensures the generated factory correctly outputs an object satisfying the full intersection type, including all required parent and variant properties.

Summary by CodeRabbit

• Tests

  • Added test coverage for handling combined schema payloads.

• Refactor

  • Improved payload generation logic for composed schemas to better support merging multiple property sources.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 3a51cce2-4ed6-4ad5-b229-d84b6f71eace

📥 Commits

Reviewing files that changed from the base of the PR and between 013b906 and 169f112.

📒 Files selected for processing (2)

• packages/core/src/generators/factory.test.ts
• packages/core/src/generators/factory.ts

---

📝 Walkthrough

Walkthrough

This PR refactors buildPayload in the factory generator to handle composed schemas (allOf/oneOf/anyOf) combined with sibling object properties. Instead of early-returning on composition keywords, fragments are accumulated and merged via Object.assign. A test case validates that oneOf payloads correctly merge with parent properties.

Changes

oneOf and object payload composition

Layer / File(s)	Summary
buildPayload refactoring for composed schemas packages/core/src/generators/factory.ts	buildPayload now accumulates payload fragments from allOf/oneOf/anyOf in an array and conditionally adds an object payload when the schema has properties. Multiple fragments are merged via Object.assign; single fragments return directly. The prior early-return behavior and the condition schemaType === 'object' || schema.properties are replaced with fragment accumulation and a simpler '{}' fallback for schema type 'object'.
Test oneOf with sibling parent properties packages/core/src/generators/factory.test.ts	New test case verifies that when a schema uses oneOf alongside top-level required properties, the generated factory output correctly merges variant and parent properties via Object.assign with expected default values.

Estimated Code Review Effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Suggested Labels

bug

Suggested Reviewers

• melloware
• snebjorn

Poem

🐰 Fragments dance in gentle arrays,
No early returns block the ways,
oneOf and siblings now unite,
Object.assign folds them tight!
Tests celebrate the merger's delight. ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ 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%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ 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 'factory methods: discriminator aliases and missing parent properties - fix' directly addresses the two main issues resolved in this PR: missing parent properties in factory generation and discriminator alias handling.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

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

[mironbalcerzak]

@melloware thanks once again 👍