ModelJS

Domain driven designed base models with flowtype support

This project is work in progress

Description

Javascript lacks good implementation of reference base models, that you can reuse in applications. While there exists attempts, to create modelling libraries, they implement only some aspects of domain driven design and lack may needed features. This module consits of three components::

• ValueObject
• Model
• Entity

ValueObject

Value object is encapsulator of arbitary object represented value with validation support. What this means it can load any json data and checks if data is correct. It has several features that ValueObjects should have:

• self validation
• immutability
• value getters

Example ValueObject

// @flow

const ValueObject = require('modeljs').ValueObject;

type User = {
	username: string;
	password: string;
}

class UserValueObject extends ValueObject<User> {
	static get schema() {
		return Joi.object({
			username: Joi.string().alphanum().required(),
			password: Joi.string().min(8).required(),
		});
	}
}

const user1 = new UserValueObject({username: 'test', password: 'password'});
user1.isValid(); // would return true

const user2 = new UserValueObject({username: 'test', password: 'short'});
user2.isValid(); // would return false since password is too short

const user3 = user2.update({password: 'newPassword'}); // update with a new value

user3.get('password') === user2.get('password'); // returns false, since ValueObject is immutable

Entity

Entity is a base model class that can be used for implementing domain application logic. It encapsulates ValueObject and provides change tracking of model data. User can provide any additional state by extending Entity object.

Example Entity

const Entity = require('modeljs').Entity;
const ValueObject = require('modeljs').ValueObject;

type User = {
	username?: string;
	password?: string;
};

type ResourceState = {
	id?: string;
	createdAt: Date;
	updatedAt?: Date;
};

class Resource<T, D: Object, S: ResourceState> extends Entity<T, D, S> {
	get InitialState() {
		return {createdAt: new Date()};
	}

	update(data: D) {
		super.update(data);
		this.state.updatedAt = new Date();
	}
}

class UserValueObject extends ValueObject<User> {
	get schema() {
		return Joi.object({
			username: Joi.string().required(),
			password: Joi.string().min(8)
		});
	}

	get updateSchema() {
		return this.schema.keys({
			username: Joi.strip()
		});
	}
}

class CreateUserValueObject extends UserValueObject {
	get schema() {
		return super.schema.requiredKeys(['password']);
	}
}

type UserState = ResourceState & {
	hashedPassword: string;
};

class UserModel extends Resource<UserModel, User, UserState> {
	get ValueObject() {
		if (this.isNew) {
			return CreateUserValueObject;
		}

		return UserValueObject;
	}

	get InitialState() {
		return {createdAt: new Date(), activated: false};
	}
}

Installation

npm install modeljs

Flowtype support

To make flowtype working in your application, do not forget to add package path to flowconfig file.

API

See API reference

License

MIT

Author

Jaka Hudoklin [email protected]