jsonschema

What is jsonschema?

The jsonschema npm package is a JSON Schema validator that can validate JavaScript objects using JSON Schemas. It is commonly used to ensure that data conforms to a predefined schema, and it can be used to validate data at runtime, as part of a testing suite, or during development to ensure data integrity.

What are jsonschema's main functionalities?

Validation

This feature allows you to validate a JavaScript object against a JSON Schema. The code sample creates a new Validator instance, defines a schema with required properties, and validates a sample data object against this schema. It outputs an empty array if the data is valid or a list of errors if it is invalid.

{"const Validator = require('jsonschema').Validator; const v = new Validator(); const schema = { 'type': 'object', 'properties': { 'name': { 'type': 'string' }, 'age': { 'type': 'integer', 'minimum': 0 } }, 'required': ['name', 'age'] }; const sampleData = { 'name': 'John Doe', 'age': 25 }; const validation = v.validate(sampleData, schema); console.log(validation.errors); // [] if valid, or list of errors if invalid."}

Custom Formats

This feature allows you to define custom formats for validation. The code sample shows how to add a custom format to the Validator instance and then use it in a schema to validate data.

{"const Validator = require('jsonschema').Validator; const v = new Validator(); v.customFormats.myFormat = function(input) { return input === 'specialValue'; }; const schema = { 'type': 'string', 'format': 'myFormat' }; const sampleData = 'specialValue'; const validation = v.validate(sampleData, schema); console.log(validation.valid); // true if valid, or false if invalid."}

Asynchronous Validation

This feature allows for asynchronous validation, which can be useful when dealing with complex validations that may require I/O operations. The code sample demonstrates how to perform validation asynchronously using a callback function.

{"const Validator = require('jsonschema').Validator; const v = new Validator(); const schema = { 'type': 'object', 'properties': { 'name': { 'type': 'string' }, 'age': { 'type': 'integer', 'minimum': 0 } }, 'required': ['name', 'age'] }; const sampleData = { 'name': 'John Doe', 'age': 25 }; v.validate(sampleData, schema, function(errors, valid) { console.log(valid); // true if valid, or false if invalid });"}

Other packages similar to jsonschema

ajv

Ajv is another popular JSON Schema validator that is known for its performance and being compliant with the JSON Schema specification. It supports all JSON Schema versions and includes features like compiling schemas for faster validation, adding custom keywords, and more. Compared to jsonschema, Ajv may offer better performance and more features.

tv4

Tiny Validator (tv4) is a lightweight JSON Schema validator. It supports draft v4 of the JSON Schema specification and is designed to be simple and easy to use. While it may not have as many features as jsonschema, it is a good choice for projects that require a minimalistic approach.

joi

Joi is a powerful schema description language and data validator for JavaScript. Unlike jsonschema, which uses JSON Schema format, Joi allows you to create validation schemas using a fluent API. It is often used for validating data in REST APIs and can be more intuitive to use for those who prefer a code-based schema definition over JSON.

README

jsonschema

Simple and fast JSON schema validator.

Usage

	var v = new Validator();
	var instance = 4;
	var schema = {"type": "number"};
	console.log(v.validate(instance, schema));

Features

Definitions

Any non ticked off definition types are ignored.

Value	JSON Schema Draft	jsonschema	Comments
type	✔	✔
properties	✔	✔
patternProperties	✔	✔
additionalProperties	✔	✔
items	✔	✔
additionalItems	✔	✔
required	✔	✔
dependencies	✔	✔
minimum	✔	✔
maximum	✔	✔
exclusiveMinimum	✔	✔
exclusiveMaximum	✔	✔
minItems	✔	✔
maxItems	✔	✔
uniqueItems	✔	✔
pattern	✔	✔
minLength	✔	✔
maxLength	✔	✔
enum	✔	✔
default	✔	✔	informational only
title	✔	✔	informational only
description	✔	✔	informational only
format	✔	✔
divisibleBy	✔	✔
disallow	✔	✔
extends	✔	✔
id	✔	✔	informational only
$ref	✔	✔
$schema	✔		ignored

Types

Value	JSON Schema Draft	jsonschema	Comments
string	✔	✔
number	✔	✔
integer	✔	✔
boolean	✔	✔
object	✔	✔
array	✔	✔
null	✔	✔
date		✔
any	✔	✔
Union Types	✔	✔

String Formats

Value	JSON Schema Draft	jsonschema	Comments
date-time	✔	✔
date	✔	✔
time	✔	✔
utc-millisec	✔	✔	Any number (integer or float) is allowed
regex	✔	✔	We test for valid regular expression
color	✔	✔
style	✔	✔
phone	✔	✔	Should follow http://en.wikipedia.org/wiki/E.123 standard.
uri	✔	✔
email	✔	✔
ip-address	✔	✔
ipv6	✔	✔
host-name	✔	✔
alpha		✔
alphanumeric		✔

Tests

Uses [https://github.com/Julian/JSON-Schema-Test-Suite](JSON Schema Test Suite) as well as our own. You'll need to update and init the git submodules:

git submodule update --init
npm test

License

jsonschema is licensed under MIT license.

Copyright (C) 2012 Tom de Grunt <[e-mail]>

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.