Setup Explicit Reverse Relationships

explicit_reverse_relations.js

var MyApp = {
    Models:{}
};

var Models = MyApp.Models;

Models.Zoo = Backbone.AssociatedModel.extend({
    relations: [{
        type: Backbone.Many,
        key: 'animals',
        relatedModel: 'Models.Animal'
    }],

    //Simulation
    sync:function (method, model, options) {
        var response = {};
        if (method === 'create') {
            response[model.idAttribute] = counter++; // dummy id
        } else if (method === 'update') {
            // Let's assume that - after success update, server sends model's json object
            response = model.toJSON();
        }
        return options.success.call(this, response);
    }

});

Models.Animal = Backbone.AssociatedModel.extend({
    relations: [{
        type: Backbone.One,
        key: 'livesIn',
        relatedModel: 'Models.Zoo'
    }]
});

var nyzoo = new Models.Zoo({id:1, name:'NY Zoo'});

nyzoo.set('animals', [
    new Models.Animal({id:101, type:'Lion', livesIn:nyzoo}),
    new Models.Animal({id:102, type:'Zebra', livesIn:nyzoo}),
    new Models.Animal({id:103, type:'Giraffe', livesIn:nyzoo})
]);
nyzoo.save();
//JSON.stringify(nyzoo); would yield
//"{"id":1,"name":"NY Zoo","animals":[
//              {"id":101,"type":"Lion","livesIn":{"id":1}},
//              {"id":102,"type":"Zebra","livesIn":{"id":1}},
//              {"id":103,"type":"Giraffe","livesIn":{"id":1}}
//]}"

See discussion here as well...