Embedded Objects vs Embedded Types in Archetype

archetype-20171013-embedded-object.js

const Archetype = require('archetype');
const assert = require('assert');

const RequestType = new Archetype({
  service: {
    $type: 'string',
    $required: true
  },
  // `location` is implicitly `$required` because
  // `type` and `coordinates` are `$required`
  // Can use a custom type for `PointType`, and
  // usually you should, but you don't have to
  location: {
    type: {
      $type: 'string',
      $required: true,
      $default: 'Point',
      $validate: v => assert.strictEqual(v, 'Point', `Invalid type ${v}`)
    },
    coordinates: {
      // Coordinates is an array of numbers
      $type: ['number'],
      $required: true,
      $validate: v => assert.equal(v.length, 2, `Must have 2 coordinates`)
    }
  }
}).compile('RequestType');

const r = new RequestType({
  service: 'Coffee Delivery',
  location: {
    // Near Northern California
    coordinates: [-122, 37]
  }
});

// Note that below, `location` is **not** an instance of PointType,
// it is just a POJO

// RequestType {
//   service: 'Coffee Delivery',
//   location: { coordinates: [ -122, 37 ], type: 'Point' } }
console.log(r);

// 'Point'
console.log(r.location.type);

archetype-20171013-embedded-type.js

const Archetype = require('archetype');
const assert = require('assert');

const PointType = new Archetype({
  type: {
    $type: 'string',
    $required: true,
    $default: 'Point',
    $validate: v => assert.strictEqual(v, 'Point', `Invalid type ${v}`)
  },
  coordinates: {
    // Coordinates is an array of numbers
    $type: ['number'],
    $required: true,
    $validate: v => assert.equal(v.length, 2, `Must have 2 coordinates`)
  }
}).compile('PointType');

const RequestType = new Archetype({
  service: {
    $type: 'string',
    $required: true
  },
  // Perfectly valid, archetypes can be embedded in other archetypes
  // Must be `$required` though, the fact that `type` is `$required`
  // for `PointType` does **not** bubble up to making `location.type`
  // `$required` for `RequestType`.
  location: {
    $type: PointType,
    $required: true
  }
}).compile('RequestType');

const r = new RequestType({
  service: 'Coffee Delivery',
  location: {
    // Near Northern California
    coordinates: [-122, 37]
  }
});

// RequestType {
//   service: 'Coffee Delivery',
//   location: PointType { coordinates: [ -122, 37 ], type: 'Point' } }
console.log(r);

// true
console.log(r.location instanceof PointType);
// 'Point'
console.log(r.location.type);