Backbone-Associative gives simple mono- or bi-directional associations to Backbone models using the hasOne, hasMany, and belongsTo association names familiar from ActiveRecord in Rails. It also lets models delegate attributes to associated models, while respecting that model's defaults and validation rules, and letting the delegating model listen to change:delegatedAttribute events. While heavily influenced by Backbone-Relational, Backbone-Associative differs in two key ways:

1. Associations (and reverse associations) are assigned in their own model classes, rather than assigning both in a single model class.
2. Associations are declared in a chained, sentence-like API, rather than by passing in an options hash.

//Backbone-Associative
House = Backbone.AssociativeModel.extend({
    associations: function() {
        this.hasMany('occupants').viaReverseKey('livesIn').modelClass('Person');
    }
});

Person = Backbone.AssociativeModel.extend({
    associations: function() {
        this.hasOne('house');
    }
});

//Backbone-Relational
House = Backbone.RelationalModel.extend({
    relations: [
        {
            type: Backbone.HasMany,
            key: 'occupants',
            relatedModel: 'Person',
            includeInJSON: Backbone.Model.prototype.idAttribute,
            collectionType: 'PersonCollection',
            reverseRelation: {
                key: 'livesIn'
            }
        }
    ]
});

Usage

To use Backbone-Associative,

1. Extend your model classes from Backbone.AssociativeModel.

2. Add an associations function as an instance property on your Backbone.AssociativeModel classes. Note: associations that depend on other associations should be specified after the associations on which they depend.

    
    Article = Backbone.AssociativeModel.extend({
        associations: function() {
            this.hasMany('comments');
        }
    });
   
    Comment = Backbone.AssociativeModel.extend({
        associations: function() {
            this.belongsTo('article');
        }
    });
    
    

3. Delegate attributes by adding a delegateAttributes instance property:

    
    Article = Backbone.AssociativeModel.extend({
        associations: function() {
            this.hasMany('comments');
        }
    });
   
    Comment = Backbone.AssociativeModel.extend({
        associations: function() {
            this.belongsTo('article');
        },
        delegateAttributes: {
            'subject': 'article'
        }
    });
    
    

Associations

• hasOne and hasMany associations indicate that another class has a reference to the class to which you assign the has association.
• belongsTo associations are the dependent side of the association. When a model's belongsTo association is destroyed, it is destroyed as well.

Options

• collection - pass a custom collection model class to be used for a hasMany association.
• viaKey means "pluck the key named X and assign it to an attribute on the model in which this association is being declared (the attribute's name is the association's name)"
• viaReverseKey means "where the model in which this association is being declared is identified by one of the space-separated keys that follow"
• as is an option passed after viaReverseKey. It means "use the associationName" to look up the class of the model in this association, but assign that model to the attribute name I'm passing in to as. Use this option when you have more than one hasOne association using the same reverseKey.
• modelClassName is an option passed after viaReverseKey. BBA will use the string passed in to this option to look up the class of the model in this association, and will then assign that model to the associationName. Use this option when you have more than one hasMany association using the same reverseKey.

Configuration

1. Backbone.AssociativeModel.namespace accepts a string or object to be used as the root namespace when looking up reverse associations.
2. Backbone.AssociativeModel.defaultCollection accepts a string or descendant of Backbone.Collection to be used as the default collection for new hasMany collections.

License

MIT. Use and enjoy!

Credits

Backbone.Associative is heavily influenced by Backbone-Relational and owes a debt of gratitude to Paul Uithol.