json-schema-to-typescript
Compile json schema to typescript typings
Example
Input:
{
"title": "Example Schema",
"type": "object",
"properties": {
"firstName": {
"type": "string"
},
"lastName": {
"type": "string"
},
"age": {
"description": "Age in years",
"type": "integer",
"minimum": 0
},
"hairColor": {
"enum": ["black", "brown", "blue"],
"type": "string"
}
},
"additionalProperties": false,
"required": ["firstName", "lastName"]
}
Output:
export interface ExampleSchema {
firstName: string;
lastName: string;
/**
* Age in years
*/
age?: number;
hairColor?: "black" | "brown" | "blue";
}
Installation
# Using Yarn:
yarn add json-schema-to-typescript
# Or, using NPM:
npm install json-schema-to-typescript --save
Usage
import { compile, compileFromFile } from 'json-schema-to-typescript'
// compile from file
compileFromFile('foo.json')
.then(ts => fs.writeFileSync('foo.d.ts', ts))
// or, compile a JS object
let mySchema = {
properties: [...]
}
compile(mySchema, 'MySchema')
.then(ts => ...)
See server demo and browser demo for full examples.
Options
compileFromFile
and compile
accept options as their last argument (all keys are optional):
key | type | default | description |
---|---|---|---|
additionalProperties | boolean | true |
Default value for additionalProperties , when it is not explicitly set |
bannerComment | string | "/* eslint-disable */\n/**\n* This file was automatically generated by json-schema-to-typescript.\n* DO NOT MODIFY IT BY HAND. Instead, modify the source JSONSchema file,\n* and run json-schema-to-typescript to regenerate this file.\n*/" |
Disclaimer comment prepended to the top of each generated file |
cwd | string | process.cwd() |
Root directory for resolving $ref s |
declareExternallyReferenced | boolean | true |
Declare external schemas referenced via $ref ? |
enableConstEnums | boolean | true |
Prepend enums with const ? |
format | boolean | true |
Format code? Set this to false to improve performance. |
ignoreMinAndMaxItems | boolean | false |
Ignore maxItems and minItems for array types, preventing tuples being generated. |
maxItems | number | 20 |
Maximum number of unioned tuples to emit when representing bounded-size array types, before falling back to emitting unbounded arrays. Increase this to improve precision of emitted types, decrease it to improve performance, or set it to -1 to ignore maxItems . |
strictIndexSignatures | boolean | false |
Append all index signatures with | undefined so that they are strictly typed. |
style | object | { bracketSpacing: false, printWidth: 120, semi: true, singleQuote: false, tabWidth: 2, trailingComma: 'none', useTabs: false } |
A Prettier configuration |
unknownAny | boolean | true |
Use unknown instead of any where possible |
unreachableDefinitions | boolean | false |
Generates code for $defs that aren't referenced by the schema. |
$refOptions | object | {} |
$RefParser Options, used when resolving $ref s |
commentStyle | 'block' | 'line' |
'block' |
Comment style for describing types. When set to line , multiline comments are collapsed to a single line. |
CLI
A CLI utility is provided with this package.
cat foo.json | json2ts > foo.d.ts
# or
json2ts foo.json > foo.d.ts
# or
json2ts foo.json foo.d.ts
# or
json2ts --input foo.json --output foo.d.ts
# or
json2ts -i foo.json -o foo.d.ts
# or (quote globs so that your shell doesn't expand them)
json2ts -i 'schemas/**/*.json'
# or
json2ts -i schemas/ -o types/
You can pass any of the options described above (including style options) as CLI flags. Boolean values can be set to false using the no-
prefix.
# generate code for definitions that aren't referenced
json2ts -i foo.json -o foo.d.ts --unreachableDefinitions
# use single quotes and disable trailing semicolons
json2ts -i foo.json -o foo.d.ts --style.singleQuote --no-style.semi
Tests
npm test
Features
- [x]
title
=>interface
- [x] Primitive types:
- [x] array
- [x] homogeneous array
- [x] boolean
- [x] integer
- [x] number
- [x] null
- [x] object
- [x] string
- [x] homogeneous enum
- [x] heterogeneous enum
- [x] Non/extensible interfaces
- [ ] Custom JSON-schema extensions
- [x] Nested properties
- [x] Schema definitions
- [x] Schema references
- [x] Local (filesystem) schema references
- [x] External (network) schema references
- [x] Add support for running in browser
- [x] default interface name
- [x] infer unnamed interface name from filename
- [x]
deprecated
- [x]
allOf
("intersection") - [x]
anyOf
("union") - [x]
oneOf
(treated likeanyOf
) - [x]
maxItems
(eg) - [x]
minItems
(eg) - [x]
additionalProperties
of type - [x]
patternProperties
(partial support) - [x]
extends
- [x]
required
properties on objects (eg) - [ ]
validateRequired
(eg) - [x] literal objects in enum (eg)
- [x] referencing schema by id (eg)
- [x] custom typescript types via
tsType
Custom schema properties:
-
tsType
: Overrides the type that's generated from the schema. Useful for forcing a type toany
or when using non-standard JSON schema extensions (eg). -
tsEnumNames
: Overrides the names used for the elements in an enum. Can also be used to create string enums (eg).
Not expressible in TypeScript:
-
dependencies
(single, multiple) -
divisibleBy
(eg) -
format
(eg) -
multipleOf
(eg) -
maximum
(eg) -
minimum
(eg) -
maxProperties
(eg) -
minProperties
(eg) -
not
/disallow
-
oneOf
("xor", useanyOf
instead) -
pattern
(string, regex) -
uniqueItems
(eg)
FAQ
JSON-Schema-to-TypeScript is crashing on my giant file. What can I do?
Prettier is known to run slowly on really big files. To skip formatting and improve performance, set the format
option to false
.
Further Reading
- JSON-schema spec: https://tools.ietf.org/html/draft-zyp-json-schema-04
- JSON-schema wiki: https://github.com/json-schema/json-schema/wiki
- JSON-schema test suite: https://github.com/json-schema/JSON-Schema-Test-Suite/blob/node
- TypeScript spec: https://github.com/Microsoft/TypeScript/blob/master/doc/spec.md