@kravc/schema

Advanced JSON schema manipulation and validation library based on z-schema.

Get Started

Install npm dependency:

npm i --save @kravc/schema

const { Schema, Validator } = require('@kravc/schema')

const userSchema = new Schema({
  firstName: { required: true },
  lastName:  { required: true }
}, 'User')

const profileSchema = userSchema
  .extend({
    status: {
      enum: [ 'Pending', 'Active' ],
      default: 'Pending'
    }
  }, 'Profile')

const validator = new Validator([ profileSchema ])

const profile = validator.validate({ firstName: 'John', lastName: 'Doe' }, 'Profile')
console.log(profile)

Expected output:

{ firstName: 'John', lastName: 'Doe', status: 'Pending' }

Other Schema and Validator usage examples:

• Schema
• Validator

Verifiable Credentials

Class CredentialFactory allows to build a verifiable credential with embeded linked data context. Common json schema types and formats (integer, date-time, etc.) are mapped to schema.org types.

Define schema for a credential subject:

const { Schema } = require('@kravc/schema')

const accountSchema = new Schema({
  id:          { required: true },
  username:    { required: true },
  createdAt:   { format: 'date-time', required: true },
  dateOfBirth: { format: 'date' }
}, 'Account')

Initialize credential factory by providing credential URI and credential subject schemas:

const { CredentialFactory } = require('@kravc/schema')

const factory = new CredentialFactory('https://example.com/schema/AccountV1', [ accountSchema ])

Create a credential for a specific subject, createCredential method validates the input and populates any defaults defined by schema:

const holder    = 'did:HOLDER_ID'
const username  = 'USER'
const createdAt =  new Date().toISOString()
const credentialId = 'https://example.com/credentials/CREDENTIAL_ID'

const subject = {
  id: holder,
  username,
  createdAt
}

const credential = factory.createCredential(credentialId, holder, subject)
console.log(JSON.stringify(credential, null, 2))

Expected JSON-LD output (could be verified using JSON-LD Playground):

{
  "@context": [
    "https://www.w3.org/2018/credentials/v1",
    {
      "AccountV1": {
        "@id": "https://example.com/schema/AccountV1"
      },
      "Account": {
        "@id": "https://example.com/schema/AccountV1#Account",
        "@context": {
          "@vocab": "https://example.com/schema/AccountV1#",
          "@version": 1.1,
          "@protected": true,
          "schema": "https://schema.org/",
          "username": {
            "@id": "username"
          },
          "createdAt": {
            "@id": "createdAt",
            "@type": "schema:DateTime"
          },
          "dateOfBirth": {
            "@id": "dateOfBirth",
            "@type": "schema:Date"
          }
        }
      }
    }
  ],
  "id": "https://example.com/credentials/CREDENTIAL_ID",
  "type": [
    "VerifiableCredential",
    "AccountV1"
  ],
  "holder": "did:HOLDER_ID",
  "credentialSubject": {
    "id": "did:HOLDER_ID",
    "username": "USER",
    "createdAt": "2020-11-11T11:11:11.111Z",
    "type": "Account"
  }
}

Attributes issuer, issuanceDate and proof are intentionally skipped and to be set by issuing function (e.g @kravc/identity).

Other CredentialFactory examples:

• createAccountCredential
• createMineSweeperScoreCredential