json-schema-to-typescript

Compile JSON Schema to TypeScript typings.

Example

Check out the live demo .

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

npm install json-schema-to-typescript

Usage

json-schema-to-typescript is easy to use via the CLI, or programmatically.

First make the CLI available using one of the following options:

# install locally, then use `npx json2ts`
npm install json-schema-to-typescript
# or install globally, then use `json2ts`
npm install json-schema-to-typescript --global
# or install to npm cache, then use `npx --package=json-schema-to-typescript json2ts`
# (you don't need to run an install command first)

Then, use the CLI to convert JSON files to TypeScript typings:

cat foo.json | json2ts > foo.d.ts
json2ts foo.json > foo.d.ts
json2ts foo.yaml foo.d.ts
json2ts --input foo.json --output foo.d.ts
json2ts -i foo.json -o foo.d.ts
# or (quote globs so that your shell doesn't expand them)
json2ts -i 'schemas/**/*.json'
json2ts -i schemas/ -o types/

You can pass any of the options described below (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

To invoke json-schema-to-typescript from your TypeScript or JavaScript program, import it and call compile or compileFromFile.

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):

default description 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 JSON Schema file,\n* and run json-schema-to-typescript to regenerate this file.\n*/" Disclaimer comment prepended to the top of each generated file customName (LinkedJSONSchema, string | undefined) => string | undefined undefined Custom function to provide a type name for a given schema string process.cwd() Root directory for resolving $refs declareExternallyReferenced boolean Declare external schemas referenced via $ref? enableConstEnums boolean Prepend enums with const? inferStringEnumKeysFromValues boolean false Create enums from JSON enums with eponymous keys format boolean 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 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 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 $refs

Tests

$ npm test

Features

title => interface

Primitive types:

array

homogeneous array

boolean

integer

number

object

string

homogeneous enum

heterogeneous enum

Non/extensible interfaces

Custom JSON-schema extensions

Nested properties

Schema definitions

Schema references

Local (filesystem) schema references

External (network) schema references

Add support for running in browser

default interface name

infer unnamed interface name from filename

deprecated

allOf ("intersection")

anyOf ("union")

oneOf (treated like anyOf)

maxItems (eg)

minItems (eg)

additionalProperties of type

patternProperties (partial support)

extends

required properties on objects (eg)

validateRequired (eg)

literal objects in enum (eg)

referencing schema by id (eg)

custom typescript types via tsType

Custom schema properties:

tsType: Overrides the type that's generated from the schema. Useful for forcing a type to any 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", use anyOf instead)

pattern (string, regex)

uniqueItems (eg)