https://github.com/susisu/type-of-schema

Derives TypeScript type from JSON Schema
https://github.com/susisu/type-of-schema

Last synced: about 2 months ago
JSON representation

Derives TypeScript type from JSON Schema

• Host: GitHub
• URL: https://github.com/susisu/type-of-schema
• Owner: susisu
• License: mit
• Created: 2020-01-10T11:51:44.000Z (almost 5 years ago)
• Default Branch: master
• Last Pushed: 2024-09-23T14:27:06.000Z (3 months ago)
• Last Synced: 2024-10-11T21:19:36.591Z (3 months ago)
• Language: TypeScript
• Homepage: https://npmjs.com/package/@susisu/type-of-schema
• Size: 194 KB
• Stars: 11
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

Awesome Lists containing this project

README

        
# @susisu/type-of-schema

[![CI](https://github.com/susisu/type-of-schema/workflows/CI/badge.svg)](https://github.com/susisu/type-of-schema/actions?query=workflow%3ACI)

Derives TypeScript type from [JSON Schema](https://json-schema.org/)

## Installation

``` shell

# npm

npm i @susisu/type-of-schema

# yarn

yarn add @susisu/type-of-schema

# pnpm

pnpm add @susisu/type-of-schema

```

## Usage

``` typescript

import type { TypeOfSchema } from "@susisu/type-of-schema";

const schema = {

  type: "object",

  properties: {

    "a": { type: "number" },

    "b": { type: "string" },

  },

  required: ["b"],

} as const;

// T = { a?: number; b: string }

type T = TypeOfSchema;

```

Do not forget `as const` in the schema declaration. Without it, you will not get the full information of the schema.

## Supported Schemas

- `const`

- `enum`

- `null`

- `number` / `integer`

- `string`

- `boolean`

- `array` (`items` and `additionalItems`) 

- `object` (`properties`, `required`, and `additionalProperties`)

- `oneOf`

- `allOf`

## Limitations

For JSON Schema object types `S` and `T`, `S extends T` does not imply `TypeOfSchema extends TypeOfSchema`. In other words, a type derived from a schema can be inconsistent with what the schema actually describes. This can be observed, for example, when upcasting a schema containing `required`:

``` typescript

const schema1 = {

  type: "object",

  required: ["a"],

} as const;

// T1 = { a: Value }

type T1 = TypeOfSchema;

const schema2: {

  type: "object";

  required: ("a" | "b")[];

} = schema1;

// T2 = { a: Value; b: Value }

// but b is actually not required

type T2 = TypeOfSchema;

```

To avoid this, do always pass the original schema to `TypeOfSchema`.

## License

[MIT License](http://opensource.org/licenses/mit-license.php)

## Author

Susisu ([GitHub](https://github.com/susisu), [Twitter](https://twitter.com/susisu2413))