JSON Schema $Ref Parser

This package needs a new maintainer or at least some contributors. For more information please read this article. As of v10.0.0 I am no longer spending any time working on this tool, so I can focus on scaling up my reforestation charity instead of burning myself out trying to maintain a whole load of OSS projects I don't use in my vanishingly small spare time. Get in touch if you'd like to take over. - Phil Sturgeon

Parse, Resolve, and Dereference JSON Schema $ref pointers

The Problem:

You've got a JSON Schema with $ref pointers to other files and/or URLs. Maybe you know all the referenced files ahead of time. Maybe you don't. Maybe some are local files, and others are remote URLs. Maybe they are a mix of JSON and YAML format. Maybe some of the files contain cross-references to each other.

{
  "definitions": {
    "person": {
      // references an external file
      "$ref": "schemas/people/Bruce-Wayne.json"
    },
    "place": {
      // references a sub-schema in an external file
      "$ref": "schemas/places.yaml#/definitions/Gotham-City"
    },
    "thing": {
      // references a URL
      "$ref": "http://wayne-enterprises.com/things/batmobile"
    },
    "color": {
      // references a value in an external file via an internal reference
      "$ref": "#/definitions/thing/properties/colors/black-as-the-night"
    }
  }
}

The Solution:

JSON Schema $Ref Parser is a full JSON Reference and JSON Pointer implementation that crawls even the most complex JSON Schemas and gives you simple, straightforward JavaScript objects.

Use JSON or YAML schemas — or even a mix of both!
Supports $ref pointers to external files and URLs, as well as custom sources such as databases
Can bundle multiple files into a single schema that only has internal $ref pointers
Can dereference your schema, producing a plain-old JavaScript object that's easy to work with
Supports circular references, nested references, back-references, and cross-references between files
Maintains object reference equality — $ref pointers to the same value always resolve to the same object instance
Tested in Node v10, v12, & v14, and all major web browsers on Windows, Mac, and Linux

Example

$RefParser.dereference(mySchema, (err, schema) => {
  if (err) {
    console.error(err);
  }
  else {
    // `schema` is just a normal JavaScript object that contains your entire JSON Schema,
    // including referenced files, combined into a single object
    console.log(schema.definitions.person.properties.firstName);
  }
})

Or use async/await syntax instead. The following example is the same as above:

try {
  let schema = await $RefParser.dereference(mySchema);
  console.log(schema.definitions.person.properties.firstName);
}
catch(err) {
  console.error(err);
}

For more detailed examples, please see the API Documentation

Installation

Install using npm:

npm install @apidevtools/json-schema-ref-parser

Usage

When using JSON Schema $Ref Parser in Node.js apps, you'll probably want to use CommonJS syntax:

const $RefParser = require("@apidevtools/json-schema-ref-parser");

When using a transpiler such as Babel or TypeScript, or a bundler such as Webpack or Rollup, you can use ECMAScript modules syntax instead:

import $RefParser from "@apidevtools/json-schema-ref-parser";

If you are using Node.js < 18, you'll need a polyfill for fetch, like node-fetch:

import fetch from "node-fetch";

globalThis.fetch = fetch;

Browser support

JSON Schema $Ref Parser supports recent versions of every major web browser. Older browsers may require Babel and/or polyfills.

To use JSON Schema $Ref Parser in a browser, you'll need to use a bundling tool such as Webpack, Rollup, Parcel, or Browserify. Some bundlers may require a bit of configuration, such as setting browser: true in rollup-plugin-resolve.

Webpack 5

Webpack 5 has dropped the default export of node core modules in favour of polyfills, you'll need to set them up yourself ( after npm-installing them ) Edit your webpack.config.js :

  config.resolve.fallback = {
    "path": require.resolve("path-browserify"),
    'util': require.resolve('util/'),
    'fs': require.resolve('browserify-fs'),
    "buffer": require.resolve("buffer/"),
    "http": require.resolve("stream-http"),
    "https": require.resolve("https-browserify"),
    "url": require.resolve("url"),
  }

  config.plugins.push(
    new webpack.ProvidePlugin({
      Buffer: [ 'buffer', 'Buffer']
    })
  )

API Documentation

Full API documentation is available right here

Contributing

I welcome any contributions, enhancements, and bug-fixes. Open an issue on GitHub and submit a pull request.

Building/Testing

To build/test the project locally on your computer:

Clone this repo
git clone https://github.com/APIDevTools/json-schema-ref-parser.git
Install dependencies
npm install
Run the tests
npm test

License

JSON Schema $Ref Parser is 100% free and open-source, under the MIT license. Use it however you want.

This package is Treeware. If you use it in production, then we ask that you buy the world a tree to thank us for our work. By contributing to the Treeware forest you’ll be creating employment for local families and restoring wildlife habitats.