bcherny/json-schema-to-typescript

Add option for generate interface with readonly properties

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#131 opened on Nov 14, 2017

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Description

The problem

I want to generate interface for object which must not be changed. I can manually wrap result using DeepReadonly type:

type DeepReadonly = {
   readonly [P in keyof T]: DeepReadonly<T[P]>;
};

but it doesn't work with arrays:

Suggestion

Add some option to json-schema-to-typescript for generating readonly properties. For example from README.md:

export interface ExampleSchema {
  readonly firstName: string;
  readonly lastName: string;
  readonly age?: number;
  readonly hairColor?: "black" | "brown" | "blue";
}

For arrays ReadonlyArray type can be used:

export interface ExampleSchema {
    readonly arr: ReadonlyArray<string>
}

Questions

Unfortunately there is no way to create read only tuple (as I known) if json-schema-to-typescript produces it.

Contributor guide

Research direction
Look at the existing codebase for type generation (e.g., src/generator.ts) and add a configuration option to enable readonly modifiers on properties and ReadonlyArray for arrays. Follow the pattern of existing options like bannerComment.
Tech stack
typescript
Domain
tooling
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.
65