@exodus/schemasafe

What is @exodus/schemasafe?

The @exodus/schemasafe npm package is a tool for validating JSON objects against JSON Schema definitions. It is designed to be secure, fast, and standards-compliant, providing developers with a reliable way to ensure that their data conforms to specified formats and rules. This package supports JSON Schema Draft-07 and offers various options for customization and optimization.

What are @exodus/schemasafe's main functionalities?

Validation

This feature allows you to validate JSON objects against a JSON Schema. The example demonstrates creating a schema for an object with 'name' and 'age' properties and then validating objects against this schema.

{"const validator = require('@exodus/schemasafe').validator;\nconst schema = {\n  type: 'object',\n  properties: {\n    name: { type: 'string' },\n    age: { type: 'number' }\n  },\n  required: ['name', 'age'],\n  additionalProperties: false\n};\n\nconst validate = validator(schema);\n\nconst valid = validate({ name: 'John Doe', age: 30 });\nconsole.log('Valid:', valid); // Valid: true\nconst invalid = validate({ name: 'John Doe' });\nconsole.log('Valid:', invalid); // Valid: false"}

Error Reporting

This feature enhances validation by including detailed error reports when validation fails. The example shows how to enable error reporting and how to access the errors after a validation attempt.

{"const validator = require('@exodus/schemasafe').validator;\nconst schema = {\n  type: 'object',\n  properties: {\n    name: { type: 'string' },\n    age: { type: 'number', minimum: 18 }\n  },\n  required: ['name', 'age']\n};\n\nconst validate = validator(schema, { includeErrors: true });\n\nconst result = validate({ name: 'John Doe', age: 17 });\nif (!result) {\n  console.log('Validation errors:', validate.errors);\n}"}

Other packages similar to @exodus/schemasafe

ajv

Ajv is a popular JSON schema validator that supports JSON Schema drafts 04, 06, 07, and 2019-09. It is known for its performance and extensive feature set, including custom keywords and asynchronous validation. Compared to @exodus/schemasafe, Ajv offers broader schema version support and additional features, but both aim to provide fast and secure JSON validation.

jsonschema

The jsonschema package is another validator that supports JSON Schema Draft-04 (with partial Draft-06 and Draft-07 support). It focuses on simplicity and compliance with the JSON Schema specification. While it may not offer the same performance optimizations as @exodus/schemasafe or Ajv, it is a solid choice for projects that prioritize strict adherence to the JSON Schema standards.

README

@exodus/schemasafe

A code-generating JSON Schema validator that attempts to be reasonably secure.

Supports draft-04/06/07/2019-09.

Installation

npm install --save @exodus/schemasafe

Usage

Simply pass a schema to compile it

const { validator } = require('@exodus/schemasafe')

const validate = validator({
  type: 'object',
  required: ['hello'],
  properties: {
    hello: {
      type: 'string'
    }
  }
})

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

Custom formats

@exodus/schemasafe 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

const validate = validator({
  type: 'string',
  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

const ext = {
  type: 'string'
}

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

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

console.log(validate('hello')) // true
console.log(validate(42)) // false

Enabling errors shows information about the source of the error

When the includeErrors option is set to true, @exodus/schemasafe also outputs:

• keywordLocation: a JSON pointer string as an URI fragment indicating which sub-schema failed, e.g. #/properties/item/type
• instanceLocation: a JSON pointer string as an URI fragment indicating which property of the object failed validation, e.g. #/item

const schema = {
  type: 'object',
  required: ['hello'],
  properties: {
    hello: {
      type: 'string'
    }
  }
}
const validate = validator(schema, { includeErrors: true })

validate({ hello: 100 });
console.log(validate.errors)
// [ { keywordLocation: '#/properties/hello/type', instanceLocation: '#/hello' } ]

Only the first error is reported by default unless allErrors option is also set to true in addition to includeErrors.

See Error handling for more information.

Generate Modules

To compile a validator function to an IIFE, call validate.toModule():

const { validator } = require('@exodus/schemasafe')

const schema = {
  type: 'string',
  format: 'hex'
}

// This works with custom formats as well.
const formats = {
  hex: (value) => /^0x[0-9A-Fa-f]*$/.test(value),
}

const validate = validator(schema, { formats })

console.log(validate.toModule())
/** Prints:
 * (function() {
 * 'use strict'
 * const format0 = (value) => /^0x[0-9A-Fa-f]*$/.test(value);
 * return (function validate(data) {
 *   if (data === undefined) data = null
 *   if (!(typeof data === "string")) return false
 *   if (!format0(data)) return false
 *   return true
 * })})();
 */

Performance

@exodus/schemasafe uses code generation to turn a JSON schema into javascript code that is easily optimizeable by v8.

See Performance for information on options that might affect performace both ways.

Previous work

This is based on a heavily rewritten version of the amazing (but outdated) is-my-json-valid by @mafintosh.

Compared to is-my-json-valid, @exodus/schemasafe adds security-first design, many new features, newer spec versions support, slimmer and more maintainable code, 0 dependencies, self-contained JS module generation, fixes bugs and adds better test coverage, and drops support for outdated Node.js versions.

License

MIT