If you are building an ecommerce site it’s likely that you’re using paypal as your payment processing method.  Paypal’s documentation is not bad, but for someone creating a paypal checkout with paypal’s Website Payments Pro package, the documentation can be somewhat overwhelming.  Once you get the hang of it, this documentation will be indispensable.

So what I’m going to explain is paypal’s express checkout feature in the Website Payments Pro package offered.  This is the paypal button that is on the cart of the website.  When clicked the user is redirected to paypal where they log into their account, choose their payment method, are then returned to the cart where they proceed to checkout. My quick disclaimer is that this is the quick and easy way of doing this.  This is just to simplify the process, not how it should actually be implemented on a production site.

First

You need to set up a developer account at developer.paypal.com. Then create a couple test accounts, one for a business and the other for a personal account. This is all pretty straight forward stuff. If you have trouble paypal also has documentation on setting up accounts in the sandbox. During this process you will be issued a Test Account, API Username, API Password, and a Signature. This information will be used when making calls to paypals server.

Second

You need a shopping cart with the paypal button on it. I’ll assume that you have this.

Third (Our form for the cart)

There is no cart in this form, but it should be.  What we have here is the paypal button at the very bottom.  The source for this image is paypal.  In the documentation you can find the specifics for using this button, but to place it on your page you can use the above code.  Everything else here is hidden form fields that contain the values that we need to send to paypal.  I’ll run through each.

User, pwd, and signature are all values that you retrieved when you set up your developer account.  This is kinda like logging in with paypal.  This just tells paypal who you are.  Also note that I’ve set these values in the Application scope as this is data that you should keep secure so it is best kept in the Application.cfc file.  This also allows you to reuse it easily.  Because they are part of the APPLICATION scope they are not included as hidden form fields. But you can see that they are passed in as variables in the code in the fourth step. Each request made to paypal will have to contain this data.  At the time of this writing the version is 52.  Paymentaction can be several things, but we’ll assume that you’re selling so it is set to Sale.  This tells paypal what type of transaction you are requesting.  Amt is the amount to be charged.  The returnurl can go anywhere you want it to go, but for us it makes the most sense for it to return to the cart so we can check the data that is sent back.  The cancelurl is the url the user will be directed to if they cancel out of paypal.  Again we have it coming back to the cart.  And lastly the all important method is set.  Paypal has three methods for the express.  The first is ‘SetExpressCheckout’.  This gets the process initiated.

The last thing I’ll mention is that the action of our form is submitting to itself.  Because of this I’ve set a variable into the URL as ppExp=true.  This is just to indicate to us when the page reruns that paypal express has been used as the payment method and we need to gather the hidden form values and send it to paypal to get this ball rolling.

Fourth (The Submission)

The idea is that when we click the paypal express button we rerun the cart.cfm page. When this happens we need to send our data to paypal and abort the processing on the page. So at the top of our cart.cfm page we need the following code.

What we need to do is make a request to paypal.  We do this by calling the ‘ppPost’ method we have stored in a cfc.  If paypal accepts everything we will get back a token.  The data we get back is in the url so we need a way to parse it and set that data into a struct that is easier to work with.  I have the code for both cfcs, which were ripped right from paypals coldfusion examples in the docs.  I cleaned them up a little bit, but they work quite well right out of the box.

ppPost Method

getNVPResponse Method

So with this token we can repost to paypal using the token to open a transaction.  The user will be sent to paypal where they will login and choose their payment type.  Since this is in the sandbox you should be able to enter the fake personal account you previously set up within the paypal sandbox.  After confirming everything you are sent back to the cart.

At any point here you can dump the contents of the getNVPResponse Method by using <cfdump var=”#VARIABLES.responseStruct#”>.  This will let you see exactly what paypal is returning to you.

Fifth (Who is the user?)

So the customer has logged in with their paypal account and been sent back to paypal. Now we need to use our new shiny token paypal sent us to get the information we need about our customer. To do this we need to make another post using the same ppPost method to make the post and the getNVPResponse method to parse the data sent back. But this time we are going to run the paypal’s GetExpressCheckoutDetails method.

First we check if we have been redirected to our cart page from paypal. We can do this by checking for a token and a payer id that was returned from paypal in the url. If so we can use our token to submit a new request to paypal to get some basic information about the user who just logged in. We create a new struct just like we did before, except this time we include the token and the method ‘GetExpressCheckoutDetails’. We use the same method to post it to paypal, and the same method to parse the url when we get our response from paypal. If we get the data from paypal successfully we need to set our data into our user’s session. We are doing this so we can have the data at hand to output on the place order page we are sending the user to. So after setting our data into the session we can redirect the user to our place_order.cfm page where they can review their cart and finalize the checkout. Again, we will pass ‘ppExp=true’ in the url so we know that our user is using paypal express.

Sixth (Show me the moolah!!)

On this page we would show our user the contents of their cart, give them a final chance to make changes to it, and allow them to submit their order. To do this we have a place order button in a form called ‘ppExpSubmit’ that submits to itself. So at the top of our page we need to check if this page has been submitted by the user to finalize their purchase.

If our user has submitted their order we need to make one last request to paypal.  The method we need to send this time is the ‘DoExpressCheckoutPayment’.  Once again create a struct and set the required information into it and send it through the ppPost method and then parse the URL with the getNVPResponse method.  Now check if the transaction was a success and if so give the user some type of confirmation.  In this case we’re moving them to a page called confirmation.cfm.

That’s it.  Once again you can do much more than what I’ve demonstrated here.  But for a basic sale this will do the job.  However, keep in mind that you should consider writing the code a little more efficiently for the sake of reuse, and at any point during this process the responses that come back through paypal can be dumped onto the screen so you can know exactly what paypal is returning to you.  Otherwise I hope this helps.