http://blog.gregwym.info/tag/paypal/ http://blog.gregwym.info/kaching.html 2013-09-01T21:57:27+08:00 Kaching is a simple payments solution for Express-based web app, inspired by Passport.js. Together with various strategies, Kaching provides a unified control flow to hook up with different online payment services.For now, Kaching only provides kaching-paypal to accepting payment through Paypal. More strategies are under plan.Install$ npm install kaching $ npm install kaching-paypal Examplehttps://github.com/gregwym/kaching/tree/master/exampleUsage0. Setup with KachingPaypal strategy require the client_id and client_secret offered by Paypal to operate. You can obtain them from https://developer.paypal.com/webapps/developer/applications.It use api.sandbox.paypal.com as the default paypal host address. Feel free to change it in production environment.var PaypalStrategy = require('kaching-paypal'); var kaching = require('kaching'); kaching.use(new PaypalStrategy({ host: '<paypal_rest_api_endpoint>', // optional port: '', // optional client_id: '<paypal_client_id>', client_secret: '<paypal_client_secret>' })); 1. Create a paymentUse kaching.create, specifying paypal strategy, to create a Paypal payment. The payment detail should be setup and saved in req.payment prior invoking the create middleware.After kaching created the pending payment, it replaces req.payment with the real payment object that was returned from Paypal API. Save it securely. (i.e., together with the user's order.)app.get('...', function(req, res, next) { // Setup payment detail in `req.payment`. req.payment = { amount:{ total:'7.47', currency:'USD' }, redirect_urls: { return_url: 'http://<return_url>', cancel_url: 'http://<cancel_url>' }, description:'Kaching paypal test transaction' }; next(); }, kaching.create('paypal', { // Optional options }), function(req, res) { // Now `req.payment` is the Paypal returned payment object res.json(req.payment); }); 2. Redirect user to Paypal to approve the paymentFor most of the time, user should redirect to Paypal to complete the payment right away. You can find the page url in payment.links and do whatever you want.Or simpler, append the kaching.approve middleware after the last request handler. It will redirect the user to the payment approval page.app.get('...', function(req, res, next) { ... }, kaching.create('paypal', { ... }), function(req, res, next) { console.log(JSON.stringify(req.payment)); next(); }, kaching.approve('paypal')); If you want to use kaching.approve somewhere else, make sure req.payment contain a valid payment object.3. Execute the approved payment to complete the transactionUser will be redirect to return_url once the payment has been approved. Paypal will specify the payer_id in req.query.PayerID. This piece of information is required to execute and complete the payment, so save it securely.Commonly, execute the payment right after can save many trouble. Here is an example,app.get('<return_route>', function(req, res, next) { // Prepare payment information and payerId req.payment = ...; // Fetch the payment object from anywhere it was saved. req.payment.payer_id = req.query.PayerID; next(); }, kaching.execute('paypal'), function(req, res) { res.json(req.payment); // Now the payment has been completed. }); Like kaching.create, kaching.execute will update req.payment to the latest. And it's up to you to deal with it.APINote: all the middleware look for the payment informations in req.payment. Make sure it is set before passing control to a middleware.PaypalStrategy(options)Construct a new strategy.var options = { host: '<paypal_rest_api_endpoint>', // optional port: '', // optional client_id: '<paypal_client_id>', client_secret: '<paypal_client_secret>' } PaypalStrategy#createBuild the payment creation middleware.It use req.payment as the payment_detail skeleton.req.payment = { intent: '[sale | authorize]', // default: sale payment_method: '[paypal | credit_card]', // default: paypal funding_instruments: { // required when payment_method = credit_card ... // https://developer.paypal.com/webapps/developer/docs/api/#fundinginstrument-object }, amount: { // required ... // https://developer.paypal.com/webapps/developer/docs/api/#amount-object }, item_list: { // optional ... // https://developer.paypal.com/webapps/developer/docs/api/#itemlist-object }, description: 'Payment description', // optional redirect_urls: { // required when payment_method = paypal return_url: ..., cancel_url: ... } }; You may notice that, things like intent, payment_method and redirect_urls are not necessarily be different for each payment. You can set the default value for them when building the middleware.... }, kaching.create('paypal', { intent: 'sale', payment_method: 'paypal', redirect_urls: { ... } }), ... Then you can omit these fields in req.payment.PaypalStrategy#approveBuild the payment approval middleware. Mainly redirect to the approval_url in payment.links.PaypalStrategy#executeBuild the approved payment execution middleware. The middleware find the payment in req.payment and execute it with req.payment.payer_id.Credits Greg Wang LicenseThe MIT LicenseCopyright (c) 2013 Greg Wang http://gregwym.info/