Integrating Payments into WordPress, Part 2: PayPal Plugins

In my previous 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.

This time I want to describe the WordPress plugin model. I’ll make some recommendations for plugins that are not only useful, but also instructive as you learn about what’s possible in WP. Then I’ll examine some of the most popular and highest rated PayPal plugins according to WP users. I’ll also identify payments functionality that might be missing or lacking in currently available plugins; we’ll go deeper into that functionality in a future article.

Extending WordPress with plugins

As the WordPress Codex succinctly puts it:

Plugins are tools to extend the functionality of WordPress

That’s a high level definition for WP users, but what about a workable definition for programmers and hackers? Here’s a better description from the Codex “Writing a Plugin” page:

A WordPress Plugin is a program, or a set of one or more functions, written in the PHP scripting language, that adds a specific set of features or services to the WordPress weblog, which can be seamlessly integrated with the weblog using access points and methods provided by the WordPress Plugin Application Program Interface (API).

The Plugin API page goes on to provide a lot of useful information on the hooks you can use to tie plugins into WordPress. These hooks falls into two basic categories, Actions and Filters. In a nutshell, actions are event based hooks (WP launches the appropriate plugin when a specific action occurs) whereas filters are text modification hooks (WP invokes these to modify text before writing the modified text to the WP database or sending it to a client browser).

Understanding how to hook a new plugin into WordPress is key for any developer interested in extending the WP system with their own functionality. The above links provide enough information for you to explore this further on your own, plus in the next installment of this series we’ll dive deeper into plugin development together. Before we do that, however, let’s look at some popular plugins, both general purpose and PayPal-related options, so you have a good understanding of what’s available and what those plugins can do.

Plugin recommendations

The definitive place to search for existing plugins is the WordPress Plugin Directory.

As of this writing, the directory contains 14,084 plugins. The directory allows you to search for plugins to meet whatever need you have for extending WP. It allows you to filter plugin search results based upon relevance, how recently plugins were added to the directory, how recently they were updated in the directory, how many WP users have downloaded them (popularity), and how highly users have rated them.

To give you a better feel for the sort of things that plugins might provide, I’ve listed a few of my favorite WP plugins below. I use these on BillDay.com and recommend them to others looking for similar functionality for their WP-powered sites. Click on the plugin name below to visit that plugin’s page in the directory to learn more about it or install it yourself.

• Advertising Manager – makes it easier to administer Google AdSense and other advertising and referral blocks
• Akismet – protects your blog from comment and trackback spam by connecting to the Akismet server and comparing with spam contributions from millions of other users (requires free Akistmet key to activate)
• FeedBurner FeedSmith – redirects your WP feeds to a FeedBurner feed so you can learn about your subscribers (link not currently available; I’m not sure if this has been updated under a different name or not)
• Feed Stats for WordPress – easy way to view statistics from your FeedBurner feed in the WP Dashboard
• Google Analytics Dashboard – shows a summary of your Google Analytics tracked activity in the WP Dashboard
• Google Analytics for WordPress – makes it easy for you to add Google Analytics tracking to your WP-powered site
• PostRank – makes it easier for you to quickly see which of your WP posts are most popular with readers, track social media analytics, and engage with site visitors from your WP Dashboard
• ShareThis – empowers your visitors to share a post or page using e-mail or posting to a great many social networks
• Twitter Tools – integrates your WordPress blog and Twitter, allowing you to import tweets into WP and/or send blog posts to Twitter; you can also optionally show your tweets in your WP sidebar, and post tweets from the WP administrative interface
• WordPress Hashcash – JavaScript which blocks spam bots

PayPal plugins

Now that you know what plugins are and how to find them in the WP directory, let’s search for PayPal related plugins to see what’s currently available.

Simply doing a naïve search for all possible related plugins using the term “PayPal” yields 313 plugins in the results. That’s a few too many to discuss each in this article!

Let’s limit the search more by changing the search term to be “PayPal shopping cart“. That gives us a much more manageable nine plugins to consider. From there we can sort by popularity and user rating.

From these searches we see that “WordPress Simple Paypal Shopping Cart” is the highest rated and the second most popular PayPal shopping cart plugin. You would click on the plugin title to examine its page and then download it if you’re interested in installing it.

Nate Sanders from the PayPal team (@ppnsanders) wrote a detailed blog post on this plugin several months ago. Click here to read Nate’s post including screenshots and details on how to use the plugin once you have it installed.

Click here to read the complete post on the PayPal X Developer Network including a look at how to accept donations using a WordPress plugin.