Building eCommerce Applications

Chapter 23. Integrating Payments into WordPress, Part 3: Build Your Own PayPal Plugin

Bill Day

This is the third and final article in my series on using the WordPress weblog and CMS system.

In the first article, I introduced WordPress (aka WP), provided links to documentation to help you get up to speed with WP, and then showed you how to install and start using it. In the second installment, I provided an overview of WP plugins, made some general plugin recommendations, and showed you how to search for PayPal-related plugins in the WordPress Plugin Directory. I also demonstrated two popular PayPal plugins—one a shopping cart, the other a plugin to accept donations.

In this article, I’ll detail the WordPress plugin model. We’ll get our hands dirty with some code for an example WordPress plugin, and by the end, you’ll know how to go about creating a simple WP plugin of your own.

A Note About PHP

To hack around in WordPress, and especially to modify or write new WP plugins, you will need to have some PHP programming knowledge. The good news is that PHP is a relatively straightforward language. There are also some very helpful resources for getting up to speed quickly with it.

If you just want a minimalist, WP-oriented introduction to PHP, I’d recommend you work through Adam Brown’s “PHP Tutorial for WordPress Users.” If you want to go further, dive into the official PHP manual and tutorial. These resources should give you the prerequisite PHP knowledge to work through the rest of this article. ...