json-schema-ref-parser

What is json-schema-ref-parser?

The json-schema-ref-parser npm package is a tool that can parse JSON Schema files and dereference $ref pointers. This allows you to combine multiple separate JSON Schema files into one resolved schema, validate JSON documents against schemas, and manipulate JSON Schemas programmatically.

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

Dereferencing $ref pointers

This feature allows you to take a JSON Schema that contains $ref pointers to other files or URLs and resolve them into a single JSON Schema object. This is useful for simplifying and flattening schemas that are spread across multiple files.

{"$ref": "http://example.com/my-schema.json"}

Bundle schemas into a single file

This feature lets you take a JSON Schema with $ref pointers to other files in your project and bundle them all into a single JSON Schema file. This can be useful for distribution or for loading a schema from a single file in a browser or other environments where multiple files are not convenient.

{"$ref": "definitions.json#/address"}

Parse JSON Schema to a JavaScript object

This feature allows you to parse a JSON Schema from a string, file, or URL into a JavaScript object. This can be useful for manipulating the schema programmatically or for using it in conjunction with other tools that operate on JavaScript objects.

{"type": "object", "properties": {"name": {"type": "string"}}}

Other packages similar to json-schema-ref-parser

ajv

Ajv is a JSON Schema validator that allows you to compile and validate JSON Schemas. It is similar to json-schema-ref-parser in that it can handle $ref pointers, but its primary focus is on validation rather than parsing and dereferencing.

json-schema

The json-schema package is another tool for validating JSON data against JSON Schemas. It is similar to json-schema-ref-parser in that it can parse and validate schemas, but it does not have the same focus on resolving $ref pointers.

tv4

Tiny Validator (tv4) is a small and fast JSON Schema validator. It is similar to json-schema-ref-parser in that it can validate JSON documents against schemas, but it does not provide the same level of support for dereferencing and bundling schemas.

README

JSON Schema $Ref Parser

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";

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.

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
   npm install

3. 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.

Big Thanks To

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