@apidevtools/json-schema-ref-parser

What is @apidevtools/json-schema-ref-parser?

The @apidevtools/json-schema-ref-parser package is a powerful tool for working with JSON Schemas. It allows users to parse JSON Schemas, resolve all $ref pointers to their corresponding values, and can bundle multiple files into a single schema. This package is particularly useful for developers working with complex JSON Schemas that include multiple references to other schemas or definitions.

What are @apidevtools/json-schema-ref-parser's main functionalities?

Dereferencing JSON Schemas

This feature allows you to take a JSON Schema that contains $ref pointers and resolve all references, resulting in a fully dereferenced schema. This is useful for understanding and validating the full structure of a schema without having to manually follow references.

{"const parser = require('@apidevtools/json-schema-ref-parser');\n\nlet schema = {\n  $ref: 'http://example.com/my-schema.json'\n};\n\nparser.dereference(schema).then(function(schema) {\n  console.log('Schema:', schema);\n}).catch(function(err) {\n  console.error(err);\n});"}

Bundling JSON Schemas

This feature bundles a JSON Schema and all its references into a single schema file. This is particularly useful for distribution or for loading a schema into tools that do not support $ref pointers.

{"const parser = require('@apidevtools/json-schema-ref-parser');\n\nlet schema = {\n  $ref: 'http://example.com/my-schema.json'\n};\n\nparser.bundle(schema).then(function(schema) {\n  console.log('Bundled schema:', schema);\n}).catch(function(err) {\n  console.error(err);\n});"}

Other packages similar to @apidevtools/json-schema-ref-parser

json-schema-resolver

Similar to @apidevtools/json-schema-ref-parser, this package focuses on resolving $ref pointers within JSON Schemas. However, it might not offer the same level of functionality for bundling schemas into a single file or the same breadth of dereferencing options.

jsonref

jsonref is another package that offers functionality to resolve $ref pointers in JSON objects, including JSON Schemas. It provides a simpler interface but may not have as comprehensive support for complex schemas or the ability to bundle schemas as @apidevtools/json-schema-ref-parser does.

README

JSON Schema $Ref Parser

Parse, Resolve, and Dereference JSON Schema $ref pointers

Installation

Install using npm:

npm install @apidevtools/json-schema-ref-parser
yarn add @apidevtools/json-schema-ref-parser
bun add @apidevtools/json-schema-ref-parser

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
• Compatible with Node LTS and beyond, and all major web browsers on Windows, Mac, and Linux

Example

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

try {
  await $RefParser.dereference(mySchema);
  // note - by default, mySchema is modified in place, and the returned value is a reference to the same object
  console.log(mySchema.definitions.person.properties.firstName);

  // if you want to avoid modifying the original schema, you can disable the `mutateInputSchema` option
  let clonedSchema = await $RefParser.dereference(mySchema, { mutateInputSchema: false });
  console.log(clonedSchema.definitions.person.properties.firstName);
} catch (err) {
  console.error(err);
}

For more detailed examples, please see the API Documentation

Polyfills

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"),
  fs: require.resolve("browserify-fs"),
};

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:

1. Clone this repo
   git clone https://github.com/APIDevTools/json-schema-ref-parser.git

2. Install dependencies
   yarn install

3. Run the tests
   yarn 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.

Big Thanks To

Thanks to these awesome companies for their support of Open Source developers ❤