Construct Object schemas and models

npm install draft
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Give your object and models schemas

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$ npm install draft --save


$ component install jwerle/draft


$ bower install draft


<script type="text/javascript" src="https://raw.github.com/jwerle/draft/master/draft.js"></script>


Creating a model with draft is as simple as passing it a schema descriptor

var User = draft({ name: String, email: String })
  , Post = draft({ owner: Object, content: String })

var werle = new User({ name: 'werle', email: 'joseph@werle.io' })
  , post  = new Post({ owner: werle, content: "I like draft :)"})


draft(descriptor, options)

Creates a schema form a descriptor and returns a model constructor


var Post = draft({
  owner    : User,
  comments : [Comment],
  content  : String,
  created  : Date,
  updated  : Date


Schema(descriptor, options)

Schema constructor

  • descriptor - An object defining a descriptor for the schema instance
  • options - An object of options:
    • strict - Strict mode. Model from schema will be frozen from schema updates after instantiation. (Default: true)


var schema = new draft.Schema({
  name: String,
  email: String

.add(key, descriptor)

Adds an object to the schema tree

  • key - A key used to identify the property in the schema
  • descriptor - An object descriptor or constructor function


schema.add({ age: Number });

.static(name, func)

Creates a static function on the schema's model constructor

  • name - The name of the static function
  • func - The actual function


var siteSchema = new draft.Schema({
  name : String,
  url  : String

siteSchema.static('createSites', function createSites (map) {
  return Object.keys(map).map(function (site) {
    return new this({ name: site, url: map[site] });
  }, this);

// create Site model
var Site = siteSchema.createModel();

var sites = Site.createSites({
  'google'  : "http://google.com",
  'github'  : "https://github.com",
  'twitter' : "https://twitter.com",

sites[0].name; // 'google'
sites[0].url; // 'http://google.com'
sites[1].name; // 'github'
sites[1].url; // 'https://github.com'


Creates a constructor from the defined schema


var schema = new draft.Schema({
  name  : String,
  email : String

var User = schema.createModel();
var user = new User({ name: 'werle', email: 'joseph@werle.io' });


Accepts an object of data and passes it to the Model constructor from the Schema instance

  • data - An object of data to pass to the schema instance model constructor


var schema = new draft.Schema({
  name   : String,
  albums : [Album],
  fans   : [Fan]

var bob = schema.new({
  name: 'bob',
  albums: [new Album({ name: "Sun Is Shining" }), new Album({ name: "Roots of a Legend" }) ],
  fans: [sally, frank, joe]

using schema descriptors

A schema descriptor is a key to type descriptor object. The key for each property on the object represents a possible key on a model instance created from the schema instance.

A simple example of a schema who defines a model which accepts an object that defines a single property name of the type string

new draft.Schema({ name : String })

A more advanced example would be to define the descriptor object for the property:

new draft.Schema({
  name: { type: String }


Tree(descriptor, options)

Tree constructor. Creates an object tree for a schema. This is used for aggregating types

A tree instance is intended to be used with a schema

  • descriptor - A schema descriptor used to define the tree.
  • options - An object of options. If present and array is set to true then an array is returned who's prototype is an instance of the tree .


var tree = new draft.Tree({
  name: String

// tree.name is an instance of draft.Type who's constructor is a String constructor
tree.name; // { Constructor: [Function: String] }

.add(parent, key, descriptor)

Adds a key to the tree on a given parent tree. Defaults to 'this' as the parent if one is not provided.

  • parent - The parent tree object in which the descriptor is added to by the provided key. Defaults to the tree instance caller.
  • key - The key of the item in the tree to add
  • descriptor - The object descriptor for the key being added to the tree


var tree = new draft.Tree({
  domain: String

tree.add('subdomains', {});
tree.subdomains; // {} (Tree instance)
tree.add(tree.subdomains, 'primary', String);
tree.subdomains.primary; // { Constructor: [Function: String] }
tree.add(tree.subdomains, 'secondary', String);
tree.subdomains.secondary; // { Constructor: [Function: String] }
tree.subdomains.add('cdn', String);
tree.subdomains.cdn; // { Constructor: [Function: String] }
tree.add('host', String);
tree.host; // { Constructor: [Function: String] }


Type(Constructor, descriptor)

Type constructor. Creates a Type used in a Tree instance for a Schema instance. It is meant to provide methods for validation and coercion.

  • Constructor - A valid type constructor who will NEVER be invoked with the new operator
  • descriptor - A valid schema constructor


var stringType = new draft.Type(String);
stringType.coerce(123); // '123'

var numberType = new draft.Type(Number);
numberType.coerce('123'); // 123

var booleanType = new draft.Type(Boolean);
booleanType.coerce(1); // true
booleanType.coerce(0); // false

Creating a custom type

var customType = new draft.Type(function CustomType (value) {
  return {
    toString: function () {
      return value.toString();

    valueOf: function () {
      return value;

    add: function (n) {
      return CustomType(value + n);

    sub: function (n) {
      return CustomType(value - n);

+customType.coerce(4).add(5); // 9
+customType.coerce(10).sub(9); // 1
customType.coerce('j').add('o').add('e').toString(); // 'joe'


Returns a string representation of a Type instance


someType.toString(); // '[object Type]'


Returns the valueOf return value from the original constructor on the Type instance

var someType.valueOf(); // some value


Default getter that coerces a value. This method that can be implemented by the descriptor. Defaults to .coerce()

var stringType = new draft.Type(String)
stringType.get(12345); // '12345'


Default setter that coerces a value. This method that can be implemented by the descriptor. Defaults to .coerce()

var stringType = new draft.Type(String)
stringType.set(12345); // '12345'


Validates a defined type. It performs instance of checks on values that are not primitive. Primitive inputs are validated with a 'typeof' check

  • input - Mixed input to validate against the type


var numberType = new draft.Type(Number)

numberType.validate('123'); // false
numberType.validate(true); // false
numberType.validate(123); // true


Coerces a given input with the set Constructor type

  • input - Input to coerce to a type


var booleanType = new draft.Type(Boolean)

booleanType.coerce(1); // true
booleanType.coerce(123); // true
booleanType.coerce(0); // false
booleanType.coerce(null); // false
booleanType.coerce(); // false


Model(data, schema)

Base constructor for all created Model instances. Usually a Model constructor is created from a schema, but passing a schema to a Model constructor works too.

  • data - An object of data is validated against the schema used to create the Model
  • schema - An instance of a schema.


var schema = new draft.Schema({
  name: String,
  email: String

var user = new draft.Model({ name: 'werle', email: 'joseph@werle.io' }, schema);


Refreshes the state of the model based on its schema


Sets data on the model based on the schema


Returns a plain object representation of the model


Called with JSON.stringify


Returns a string representation of a Model instance


Returns a value representation of a Model instance



Define a schema for an object with types. Strict mode default

var draft = require('draft')
var schema = new draft.Schema({
  name : String,
  profile : {
    email : String,
    age : Number

Create a model constructor from the schema defaulting to strict mode

var User = schema.createModel();

Instantiate the model passing in an object. In strict mode all properties on an object must be defined in the schema that was used to create it

var user = new User({
  name: 'werle',
  profile: { email: 'joseph@werle.io' },
  somePropertyNotInSchema: 'someValue'

Only values in the schema were set on the object

user.name // werle
user.profile.email // joseph@werle.io
user.somePropertyNotInSchema // undefined


  • write more tests
  • document more



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