Merstone

A data-model abstraction. This is a base class for models. You can construct one if all you want to do is observe some data, or you can extend it if you want that and more.

If you have used Backbone before, Merstone models will be familiar to you. The main difference is that where Backbone models are "active record"-like, i.e. they correspond to an API and deal with persistence, Merstone models are not. They don't have any functionality pertaining to persistence at all. They are intended to be used in a service oriented architecture, i.e you call model.toJSON() and pass that to a service for persistence. This allows greater flexibility, but still allows you to extend the models and build in behaviour like save() and fetch() should you wish.

Merstone models inherit their eventy behaviour from node event emitter.

Installation

npm install --save merstone

Usage

//
// Constructor
//

var Model = require('merstone')
  , m = new Model(serviceLocator, {})

//
// Getting, setting and resetting
//

m.get('name')

m.set('name', 'Ben')
m.set({ firstName: 'Ben', lastName: 'Gourley'})

m.reset({ firstName: 'Cara', lastName: 'Haines'})

//
// Events
//

m.on('change', function (model) {
  console.log('An attribute changed on model ' + model.id)
})

m.on('change:name', function (value, model) {
  console.log('Name attribute is now ' + value + ' on model ' + model.id)
})

m.on('reset', function (model) {
  console.log('model ' + model.id + ' attributes were reset')
})

//
// Serialisation
//

// Creates a deep clone of the model's attributes
m.toJSON()

//
// Hooks
//

// 'preSet'
// These hooks are run on .set() before the model attributes are updated
// Accepting raw user input? Maybe you want to do some type casting…

m.hook('preSet', castNumbers)

function castNumbers(attributes, cb) {
  // Do something to the attributes
  if (attributes.age) attributes.age = parseInt(attributes.age, 10)
  cb(null, attributes)
}

Extending Merstone for your own models

Merstone doesn't do any fancy extend-y stuff, you just use built-in JS prototypal inheritence methods.

module.exports = ClockModel

var Model = require('merstone')

function ClockModel(serviceLocator, attributes) {
  // Call the model constructor
  Model.apply(this, arguments)
}

// Set the object prototype
ClockModel.prototype = Object.create(Model.prototype)

// Now add custom methods to the new prototype

ClockModel.prototype.tick = function () {
  console.log('tick')
}

ClockModel.prototype.tock = function () {
  console.log('tock')
}

var ClockModel = require('./clock-model')
  , m = new ClockModel(serviceLocator)

The name?

I've made a bunch of MVC-like components. I named each one after villages on the Isle of Wight (where I live) beginning with the same letter as the thing it represents.

See also Ventnor views and Chale collections.

Credits

• Ben Gourley

Licence

Copyright (c) 2014, Ben Gourley

Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.