var loopback = require('../../'); var CartItem = exports.CartItem = loopback.PersistedModel.extend('CartItem', { tax: {type: Number, default: 0.1}, price: Number, item: String, qty: {type: Number, default: 0}, cartId: Number }); CartItem.sum = function(cartId, callback) { this.find({where: {cartId: 1}}, function(err, items) { var total = items .map(function(item) { return item.total(); }) .reduce(function(cur, prev) { return prev + cur; }, 0); callback(null, total); }); } CartItem.remoteMethod('sum', { accepts: {arg: 'cartId', type: 'number'}, returns: {arg: 'total', type: 'number'} } ); CartItem.prototype.total = function() { return this.price * this.qty * 1 + this.tax; }