is-my-json-valid

What is is-my-json-valid?

The is-my-json-valid npm package is a JSON schema validator that is fast and simple to use. It allows you to validate JSON data against a schema, ensuring that the data conforms to the expected structure and types.

What are is-my-json-valid's main functionalities?

Basic JSON Validation

This feature allows you to validate a simple JSON object against a schema. In this example, the schema expects an object with a string 'name' and a number 'age'. The provided JSON object meets these criteria, so the validation returns true.

const validator = require('is-my-json-valid');
const validate = validator({ type: 'object', properties: { name: { type: 'string' }, age: { type: 'number' } } });
const valid = validate({ name: 'John', age: 30 });
console.log(valid); // true

Custom Error Messages

This feature provides detailed error messages when validation fails. In this example, the 'age' property is a string instead of a number, so the validation fails and the errors are logged.

const validator = require('is-my-json-valid');
const validate = validator({ type: 'object', properties: { name: { type: 'string' }, age: { type: 'number' } } }, { verbose: true });
const valid = validate({ name: 'John', age: 'thirty' });
if (!valid) console.log(validate.errors);

Formats and Custom Formats

This feature allows you to use predefined formats like 'email' to validate specific types of strings. In this example, the 'email' property must be a valid email address.

const validator = require('is-my-json-valid');
const validate = validator({ type: 'object', properties: { email: { type: 'string', format: 'email' } } });
const valid = validate({ email: '[e-mail]' });
console.log(valid); // true

Other packages similar to is-my-json-valid

ajv

AJV (Another JSON Schema Validator) is a highly efficient and feature-rich JSON schema validator. It supports JSON Schema draft-07 and provides advanced features like asynchronous validation, custom keywords, and more. Compared to is-my-json-valid, AJV offers more extensive support for JSON Schema specifications and additional features.

jsonschema

The jsonschema package is a simple and easy-to-use JSON schema validator. It supports JSON Schema draft-04 and is suitable for basic validation needs. While it may not be as fast as is-my-json-valid, it provides a straightforward API for validating JSON data.

joi

Joi is a powerful schema description language and data validator for JavaScript objects. It allows you to define schemas using a fluent API and provides extensive validation capabilities. Unlike is-my-json-valid, Joi is not limited to JSON Schema and offers more flexibility in defining and validating data structures.

README

is-my-json-valid

A JSONSchema validator that uses code generation to be extremely fast

npm install is-my-json-valid

It passes the entire JSONSchema v4 test suite except for remoteRefs and maxLength/minLength when using unicode surrogate pairs.

Usage

Simply pass a schema to compile it

var validator = require('is-my-json-valid')

var validate = validator({
  required: true,
  type: 'object',
  properties: {
    hello: {
      required: true,
      type: 'string'
    }
  }
})

console.log('should be valid', validate({hello: 'world'}))
console.log('should not be valid', validate({}))

// get the last list of errors by checking validate.errors
// the following will print [{field: 'data.hello', message: 'is required'}]
console.log(validate.errors)

You can also pass the schema as a string

var validate = validate('{"type": ... }')

Optionally you can use the require submodule to load a schema from __dirname

var validator = require('is-my-json-valid/require')
var validate = validator('my-schema.json')

Custom formats

is-my-json-valid supports the formats specified in JSON schema v4 (such as date-time). If you want to add your own custom formats pass them as the formats options to the validator

var validate = validator({
  type: 'string',
  required: true,
  format: 'only-a'
}, {
  formats: {
    'only-a': /^a+$/
  }
})

console.log(validate('aa')) // true
console.log(validate('ab')) // false

External schemas

You can pass in external schemas that you reference using the $ref attribute as the schemas option

var ext = {
  required: true,
  type: 'string'
}

var schema = {
  $ref: '#ext' // references another schema called ext
}

// pass the external schemas as an option
var validate = validate(schema, {schemas: {ext: ext}})

validate('hello') // returns true
validate(42) // return false

Filtering away additional properties

is-my-json-valid supports filtering away properties not in the schema

var filter = validator.filter({
  required: true,
  type: 'object',
  properties: {
    hello: {type: 'string', required: true}
  },
  additionalProperties: false
})

var doc = {hello: 'world', notInSchema: true}
console.log(filter(doc)) // {hello: 'world'}

Verbose mode outputs the value on errors

is-my-json-valid outputs the value causing an error when verbose is set to true

var validate = validator({
  required: true,
  type: 'object',
  properties: {
    hello: {
      required: true,
      type: 'string'
    }
  }
}, {
  verbose: true
})

validate({hello: 100});
console.log(validate.errors) // {field: 'data.hello', message: 'is the wrong type', value: 100}

Greedy mode tries to validate as much as possible

By default is-my-json-valid bails on first validation error but when greedy is set to true it tries to validate as much as possible:

var validate = validator({
  type: 'object',
  properties: {
    x: {
      type: 'number'
    }
  },
  required: ['x', 'y']
}, {
  greedy: true
});

validate({x: 'string'});
console.log(validate.errors) // [{field: 'data.y', message: 'is required'},
                             //  {field: 'data.x', message: 'is the wrong type'}]

Performance

is-my-json-valid uses code generation to turn your JSON schema into basic javascript code that is easily optimizeable by v8.

At the time of writing, is-my-json-valid is the fastest validator when running

• json-schema-benchmark
• cosmicreals.com benchmark
• jsck benchmark
• themis benchmark
• z-schema benchmark

If you know any other relevant benchmarks open a PR and I'll add them.

License

MIT