Backbone-attribute-types NPM

Backbone Attribute Types

A non-obtrusive plugin that extends models to force get()ing of attributes to return values in a specific type (integer, date, etc).

Example Usage

var TypedModel = Backbone.Model.extend({

	attrTypes: {
		'count': 'int',
		'runtime': 'float',
		'created_at': 'moment'
	}

});

var typedModel = new TypedModel({
	count: '10',
	runtime: '4.75',
	created_at: '2017-09-19'
})

typedModel.get('count') // 10
typedModel.get('runtime') // 4.75
typedModel.get('created_at') // date object

// a use-case
typedModel.attributes['count'] + 9 // = "109" (this would normally happen)
typedModel.get('count') + 9 // = 19

Attribute Types `attrTypes`

There are default attribute types under Backbone.ModelAttrTypes. You can add to this or specify a custom type on the model.

attrTypes can also be defined on the Collection.

Supported Types

window.Backbone.ModelAttrTypes = {
	'string': function(val){ return String(val) },
	'json': function(val){ return _.isString(val) ? JSON.parse(val) : val },
	'bool': function(val){ return !!val },
	'int': function(val){ return parseInt(val) },
	'float': function(val){ return parseFloat(val) },
	'num': function(val){ return parseFloat(val) }, // alias for float
	'date': function(val){ return new Date(val) },
	// moment.js support
	'moment': function(val){ return window.moment ? moment(val) : new Date(val) }
}

Custom Types

var CustomTypedModel = Backbone.Model.extend({

	attrTypes: {
		'attrName': function(val){
			// convert val to type
			return val
		}
	}

});

Casting to type

You can cast an attribute to a type on the fly by appending a pipe | and the type at the end of the attribute name.

typedModel.get('runtime') // 4.75
typedModel.get('runtime|int') // 4
typedModel.get('runtime|string') // "4.75"

You can also cast as raw to get the original value stored in attributes

typedModel.get('runtime|raw') // "4.75"

Why?

The reason for this plugin is for when your model has an attribute in a string format (for JSON and database consistency) but you wish to use the value in code as a certain type. Rather than 1) continually converting the value to your desired type or 2) creating a secondary method to make this conversion, this plugin will do it for you.

It's designed to be non-obtrusive by refraining from overwriting the real value in attributes and allows you to continue using .get(attr) like normal.