Backbone.associate

Presumptionless model relations for Backbone in < 1kb.

Usage

Use Backbone.associate to define relationships between application models and collections.

var Flag = Backbone.Model.Extend({ /* ... */ }),
    City = Backbone.Model.Extend({ /* ... */ }),
    Cities = Backbone.Collection.extend({ model: City }),
    Country = Backbone.Model.Extend({ /* ... */ });

Backbone.associate(Country, {
  flag: { type: Flag },
  cities: { type: Cities }
});

Here, we're associating a model (Country) with two relations: a Flag model and a collection of Cities. The association keys can be anything, but they should match the keys used in the data that will be passed into the application's parse method.

var canada = new Counry({
  flag: { 
    colors: ['red','white'] 
  },
  cities: [
    { name: 'Calgary' },
    { name: 'Regina' }
  ]
});

When it's time to sync the parent resource back up with the server, child resources can be serialized and included in the request.

canada.toJSON(); // { flag: { colors: ['red','white'] }, ...

Since associates are just attributes, they may be accessed at any time using the usual get. For the truly lazy, associate also extends the base model with an accessor for each association:

canada.flag().set({ colors: ['red','white'] });
canada.cities().add([
  { name: 'Edmonton' },
  { name: 'Montreal' },
  { name: 'Ottawa' },
  { name: 'Vancouver' }
]);

That's handy for manipulating the relations, setting up eventing, or any of the many other things this plugin won't do for you. Speaking of which,

Things this plugin won't do...

...include configuring child URLs, identity mapping, and making any other kinds of presumptions about how it will be used. Fortunately, all of these can be implemented as needed (fiddle here):

Configure child URLs

canada.cities().urlRoot = canada.url() + '/cities'
canada.flag().url = canada.url() + '/flag'

Identity mapping

var getCountry = function (id) {
  _countries = {};
  return (getCountry = function (id) {
    if (!_countries[id]) {
      _countries[id] = new Country({ id : id });
    }
    return _countries[id];
  })(id);
};

Child events

canada.onCityAdded = function (model) {
  console.log('city added!', model.get('name'));
}

canada.listenTo(canada.cities(), 'add', canada.onCityAdded);

Testing

Specs are implemented with jasmine-node. After cloning this repo, install dependencies and test with npm.

$ npm install
$ npm test

Contributing

Have something to add? Contributions are enormously welcome!

Fork this repo
Update the spec and implement the change
Submit a pull request

License

Backbone.associate is released under the terms of the MIT license

magnusvk/backbone.associate