models.js

	var OrderItemSet = Backbone.Collection.extend({
		model: function(data, options)
		{
			var isAccountLevel = _.has(data._embedded.product, 'isAccountLevel')
				&& data._embedded.product.isAccountLevel;
			var subType = data.subType || null;
			var orderItemFunction = OrderItem.factory(data.orderItemType, subType, isAccountLevel);
			return new orderItemFunction(data, _.clone(options));
		},

		initialize: function()
		{
			// Massive hack needed for backbone 1.1.2 because it has a bug that means
			// when a function is supplied for model you can't use custom id attributes.
			// This is fixed in 1.2.0 by using the modelId attribute (see below) but at
			// the time of writing nestedtypes was not working correctly with backbone 1.2.0
			this.model.prototype.idAttribute = 'uid';

			this.on('refetch', function(){_.defer(function(item){item.fetch()}, this);}, this);
		},

		// this is the correct way to specify the model id attribute when the model
		// attribute is a factory function rather than a model constructor. This
		// should work from backbone 1.2.0. See the hack in initialize for backbone 1.1.2.
		modelId: function (attrs) {
			return 'uid';
		},