bcherny/json-schema-to-typescript

Option for adding `undefined` to optional union for optional properties.

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#604 opened on Jun 23, 2024

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Description

In TypeScript, when exactOptionalPropertyTypes is set to true, properties that are optional?: but not do not include | undefined in their union can not be assigned a value of undefined.

For generating code that will be consumed by others, we may not want to force them to turn off exactOptionalPropertyTypes. For that please consider an option to include undefined in generated type unions of non-required properties.

Contributor guide

Research direction
Examine the codebase for how optional properties are generated in the output TypeScript types. Identify the current logic that omits `undefined` from unions. Design an option to include `undefined` when `exactOptionalPropertyTypes` is enabled.
Tech stack
typescript
Domain
developer experiencetooling
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
TypeScriptJSON Schema
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70