Google Checkout Integration

© 2007 Mike Wills Learning Services

I had some difficulties with integrating with my shopping cart software with Google Checkout. With PayPal it was easy — I just got my program to modify the code for one of the 'Buy Now' buttons. Unfortunately, the Google Checkout button code is encrypted which means I would have to produce a different button for every one of my items.

So I tried using Google's API sample code, but the test URL was not recognised and the live code produced an error. I gave up on trying the sandbox (test area) and concentrated on getting the live code to work. After delving deeper into the Developers' Handbook, I have managed to sort the problem out:

The samples Google give are for a US shopping basket but as my account is in Pounds stirling the orders were rejected. The US Dollar is the default currency so the code to define the currency was not included in the sample. I managed to solve the problem by adding these two lines of code:

<input type="hidden" name="item_currency_1" value="GBP">
<input type="hidden" name="ship_method_currency_1" value="GBP">

To convert the test code into a live code, you need to replace the first line with:

<form method="POST" action="https://checkout.google.com/cws/v2/Merchant/YOUR_MERCHANT_NUMBER/checkoutForm" accept-charset="utf-8">

Don't forget to put in your own merchant number both in this line and in the following line:

<input type="image" name="Google Checkout" alt="Fast checkout through Google" src="http://checkout.google.com/buttons/checkout.gif?merchant_id=YOUR_MERCHANT_NUMBER&w=180&h=46&style=white&variant=text&loc=en_US" height="46" width="180"/>

I also removed the two lines referring to the tax_rate and tax_us_state as VAT is not chargeable on books.

You should also bear in mind that Google insist that customers should not have to provide any data before they can click on a Google 'Checkout' or 'Buy Now' button. This includes sign-in/log-on pages and even giving an email address. This policy makes integrating Google Checkout with your own shopping cart much harder and makes order processing take longer if you maintain your own order and customer database. Presently, Google are not closing accounts which go against this policy, but they will not put a 'Google Checkout' badge on your Adwords advertisements.


Also see:
Credit Card Processing