Easen Models

How to use

Create your first model

Firstly, you have to create your own model:

const { createModel, types: t } = require('easen-models')

const Post = createModel({
  id: t.int,
  title: t.string,
  published: t.bool,
  createdAt: t.date,
  updatedAt: t.date
})

Use model

Secondly, just create instance of this model:

const post = new Post({
  id: '10',
  title: 'Post title',
  published: 1,
  createdAt: '2017-01-01T15:00:00',
  updatedAt: Date.now()
})

Handle validation errors

In case of current types, values will be transformed to correct type (e.g. id to int). When something will be wrong, ModelValidationError will be thrown, so you can handle errors:

const { ModelValidationError } = require('easen-models')

try {
  const post = new Post({
    id: '10',
    title: 'Post title',
    published: 1,
    createdAt: '2017-01-01T15:00:00',
    updatedAt: Date.now()
  })
} catch (e) {
  if (e.name === 'ModelValidationError') {
    // Some values are wrong, you can look at additional errors at e.list
    // Or you can dump whole error with e.toJSON() method
  } else {
    // Rethrow errors not connected to validation
    throw e
  }
}

Prepare your own validators

Behind the scenes, models are trying to instantiate values and checks for errors. Let see some examples of preparing your own validators:

const { createModel, types: t } = require('easen-models')

const Post = createModel({
  id: t.int.assert(v => v < 10, 'ID must be smaller than 10'),
  title: t.string.pass(v => v.toUpperCase()),
  published: t.assert(v => v === true, 'Post must be published'),
  likesPercentage: t.pass(parseFloat).pass(v => v * 100),
  slug: v => ('' + v).toLowerCase().replace(/[^a-z]/g, '-')
})

Validators/types are just simple functions, which can throw error. It means, that you can use any other libraries to use there. When Model will detect error thrown, it will throw ModelValidationError.

Alternatively, you can use simple syntax with pass & assert helpers. Every validation included in easen-models allow chaining by default. pass is just passing a value to next function, assert will make assertion (check if passed function results with truthy value) and throw error if not. You can use these methods as many times in chain you want.

Updating object

You have to simply update a value - it will be automatically transformed. Everything is using getters & setters:

const { createModel, types: t } = require('easen-models')

const Post = createModel({
  id: t.int,
  title: t.string,
  published: t.bool,
  createdAt: t.date,
  updatedAt: t.date
})

const post = new Post({
  id: '10',
  title: 'Post title',
  published: 1,
  createdAt: '2017-01-01T15:00:00',
  updatedAt: Date.now()
})

console.log(post.createdAt) // instance of Date, 2017-01-01T15:00:00.000Z

post.createdAt = '2015-01-01'
console.log(post.createdAt) // instance of Date, 2015-01-01T00:00:00.000Z

Getting raw object

You can get copy of raw object using built-in function:

const { raw } = require('easen-models')
const value = raw(post)

If you want to serialize object, you can simply use just JSON.stringify

Development

Mocha with Expect.js are used for tests, with Wallaby as additional runner for development. Code style standard is StandardJS.

To do

• Write unit tests
• Extend description, improve documentation
• Write oneOfType validator
• Prepare table with available validators in README file