bulksave method for Alloy collection

foo.js

exports.definition = {
	config: {
		'columns': {
			'bar': 'text'
		},
		'adapter': {
			'type': 'sql',
			'collection_name': 'foo'
		}
	},

	extendModel : function(Model) {
		_.extend(Model.prototype, {
		});

		return Model;
	},

	extendCollection : function(Collection) {
		_.extend(Collection.prototype, {
			bulksave: function(values) {
				values = values || [];

				var db, sql, c = [], q = [], len = values.length;
				for (var k in this.config.columns) {
					c.push(k);
					q.push('?');
				}

				sql = 'REPLACE INTO ' + this.config.adapter.collection_name +
					' (' + c.join(',') + ') VALUES (' + q.join(',') + ')';

				db = Ti.Database.open(this.config.adapter.db_name || ALLOY_DB_DEFAULT);
				db.execute('BEGIN TRANSACTION');

				for (var i = 0; i < len; i++) {
					db.execute(sql, values[i]);
				}

				db.execute('COMMIT');
				db.close();

				this.trigger('bulksave');
			}
		});

		return Collection;
	}
};