A/B testing is a process by which multiple variants of a website are presented to different users randomly and statistical tools are used to see whether any variant is more effective, according to an overall goal metric such as conversions or revenue.

While various A/B testing products—many free—exist, none are made from the ground up to work within the WordPress ecosystem. I believe a solution made particularly for WordPress could make A/B testing so much easier and more straightforward, and that such a solution could be greatly beneficial to the platform as a whole.

I’m happy to announce my new project, code-named ShrimpTest,¹ which is directly aimed at filling this void. I’ll be working on this project this summer together with the fantastic folks at Automattic.

The best way to keep up with development is on the project’s development blog, the ShrimpTest P2. Most updates will most likely be much shorter than this initial post. You can get less frequent, milestone-like updates by following ShrimpTest on twitter. Development will be open so feel free to check it out (haha) and submit patches as well. As I go along, I’ll also look forward to your feedback.

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WordPress itself is built on a powerful plugin API which provides actions and filters. Actions correspond to events, so you can set a webhook to fire when a post is published or a comment is made.¹ Filters let you modify some text when it is saved or displayed, so you can have your external webhook script reformat some text or insert some other content dynamically. Not all actions and filters are supported at this time, but I will continue to add more in.

There’s a webhooks meetup in San Francisco today but I unfortunately left SF this morning, so I created a video which will be played there as a lightning talk. A demo of both types of webhooks are in the video as well.

HookPress: add webhooks to WordPress from mitcho on Vimeo.

I’m really excited by this very simple but potentially high-impact plugin. I’d love to get your comments and feedback on this new plugin and hope to hear how you’re using HookPress!

ADDENDUM: Please also follow HookPress on twitter!

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A new user of my WordPress plugin tipped me off to a recent Tekzilla segment where WordPress founder Matt Mullenweg recommended Yet Another Related Posts Plugin as one of his personal favorite WordPress plugins. Thanks Matt! ^^

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A while back I created a count command for Ubiquity to count HTML elements on a page, so I’ll share it here. The idea is super simple: select some text on your page and execute count p to get the number of paragraphs, or count a to get the number of links, or count tr to get the number of table rows. This is super useful when reading articles with charts or lists online and you want to know how many there are without doing something like copy-pasting into Excel.

The count command is built using jQuery so it can even understand targets like p.class or a[href=...]. Give it a try! ^^

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In order to introduce an external ordering source, we need to do four things: 1. create the external ordering source, 2. hook up (read “join”) the external ordering source 3. make sure we use that order, and 4. make it play nice. ^^

By the way, I’m going to assume you, dear reader, are PHP-savvy, proficient in MySQL, and already know a little about WordPress. This how-to is not for the PHPhobic.

The ordering source

For this example, suppose we want to display posts by order of “interestingness.” We’ll just create a table called wp_interestingness with two columns, ID and interestingness and populate it with some data. We’ll even be nice to our database by making sure the ID is the primary key. Easy.

Hook up the external ordering source

When you run a query through query_posts() (or use WP_Query’s query method²), what it’s doing is taking your special request and translating it into a MySQL statement. This means a query like "monthnum=1" is turned into SELECT ... wp_posts.* FROM wp_posts WHERE 1=1 AND MONTH(wp_posts.post_date)='1' .... Every different query introduces something new to the basic SELECT command—in this case, the AND MONTH(wp_posts.post_date)='1'.

We first want to introduce the interestingness for each post and that means joining the new table into the query. We’ll do this using the posts_join filter. This filter lets you add a join statement to the MySQL request.

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add_filter('posts_join','my_join_filter');
function my_join_filter($arg) {
	$arg .= " natural join wp_interestingness ";
	return $arg;
}

Note that here we’re using natural join as wp_posts and wp_interestingness have only one key in common, ID, and that’s exactly the column we want to join them on.

Use the new order

Now that we’ve joined wp_interestingness in, we can refer to wp_interestingness.interestingness in our query. Note now that, by default, an $wpdb->posts.post_date will be used to order the posts. We’ll use another filter here; this time posts_orderby, to patch this part of the query. We’ll search for the default ORDER BY value and replace it with our own interestingness.

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add_filter('posts_orderby','my_orderby_filter');
function my_orderby_filter($arg) {
	global $wpdb;
	$arg = str_replace("$wpdb->posts.post_date","wp_interestingness.interestingness",$arg);
	return $arg;
}

By the way, you can now check the resulting MySQL query by echoing $wp_query->request. (If you’re using the WP_Query method I advocated below in footnote (2), you’ll of course have to change $wp_query to the WP_Query object you’re using.)

Learn to play nice ^^

The instructions above do indeed work, but they also cause some major breakdowns in other functions of your blog. Why? That’s because the current code will edit your queries for every instance of The Loop: your index page, your archives, and your RSS feeds. You probably only want to search by interestingness in certain situations. What we need is a way to tell our (admittedly stupid) my_join_filter and my_orderby_filter when they should apply their interestingness magic and when they shouldn’t. There are several ways to set up such a system but here I’ll lay out one that I feel is particularly elegant. We’ll set it up so you can actually use query_posts("orderby=interestingness") and it’ll know what you’re talking about.

One of the first things that happens in query_posts—indeed, way before even the posts_join and posts_orderby filters—is an action hook called parse_query. This lets us look at the initial state of the WP_Query object as it starts to run. In particular, we can look at the orderby query variable and see if we want to order by interestingness. If we do, we’ll set a global variable called $use_interestingness_flag to be true.

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add_action('parse_query','set_use_interestingness_flag');
function set_use_interestingness_flag($query) {
	global $use_interestingness_flag;
	if ($query->query_vars['orderby'] == 'interestingness')
		$yarpp_score_override = true;
	else
		$yarpp_score_override = false;
}

Now we just have to edit our filters so they only run when $use_interestingness_flag == true. We also will make sure to turn the flag back off in my_orderby_filter, as it’s our last filter to run during each query. It’s just like putting the seat back down after using a unisex bathroom.³

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add_filter('posts_join','my_join_filter');
function my_join_filter($arg) {
	global $use_interestingness_flag;
	if ($use_interestingness_flag)
		$arg .= " natural join wp_interestingness ";
	return $arg;
}
add_filter('posts_orderby','my_orderby_filter');
function my_orderby_filter($arg) {
	global $wpdb, $use_interestingness_flag;
	if ($use_interestingness_flag)
		$arg = str_replace("$wpdb->posts.post_date","wp_interestingness.interestingness",$arg);
	$use_interestingness_flag = false;
	return $arg;
}

This method has a great advantage as you can just set it up once and invoke it whenever you want, even together with other parameters, without any additional code. For example, you can try query_posts("monthnum=1&orderby=interestingness") or query_posts("cat=-529&orderby=interestingness").

Conclusion

Adding an external ordering source to your WordPress post queries can be relatively straightforward if you understand what query_posts does and take advantage of its hooks. This tutorial can also serve as the basis for many other patches to WP_Query, not just the orderby parameter. To better understand the way WordPress builds its MySQL queries and the many posts_* filters which you can take advantage of, go to the source: wp-includes/query.php. Finally, you can use the special parse_query hook and global variables as flags to only apply the filters when necessary.

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Clicking on a version’s permalink will let you download the plugin. Subscribe now and be the first to find out when the upcoming version 2.1 is released!

I decided to semi-automate this RSS-producing process as well. As a plugin developer using wordpress.org’s plugin hosting, I sync a local copy of the plugin to their server using SVN. I wrote a PHP script to get the modification date information directly from the local files, parse the version log in the read me, and produce the RSS feed. If there’s an interest, perhaps I’ll release this code in the future.

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Well, it’s been a while since I updated my plugin YARPP—in my humble opinion the best related posts plugin for WordPress. ^^ Today I release version 2.0, incorporating a number of important requests and bug fixes:

• New algorithm which considers tags and categories, by frequent request
• Order by score, date, or title, by request
• Excluding certain tags or categories, by request
• Sample output displayed in the options screen
• Bugfix: an excerpt length bug
• Bugfix: now compatible with the following plugins:
  • diggZEt
  • WP-Syntax
  • Viper’s Video Quicktags
  • WP-CodeBox
  • WP shortcodes

Check out the Yet Another Related Posts Plugin page on this site, the page on wordpress.org, or download it directly now!

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I like many others am a big fan of John Gruber’s Markdown, a simple typesetting spec for entering text in a clean, legible plain-text fashion and outputting to (X)HTML. Michel Fortin did the fabulous job of porting the Markdown engine to PHP, making it a plugin for WordPress, bBlog, and TextPattern.

I’ve been using Markdown for all my blog posts here. Recently, though, I was in charge of a bbPress bulletin board (the “less is more” sister project to WordPress) for the Shoreland Scav Hunt team, and wanted to use Markdown formatting there. And I wasn’t the only one wanting to do this.

With some experimenting and research into the filters in the bbPress text flow (different than the WordPress one), I was able to make Markdown work in bbPress. This involved adding a special bbPress plugin wrapper to Michel Fortin’s PHP Markdown Extra. I’ve rereleased this plugin as Markdown for WordPress and bbPress, available at both wordpress.org and bbpress.org. Enjoy!

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This posting is now outdated… for the latest information on YARPP, please visit YARPP’s very own page on my site, or its page on wordpress.org. If you have questions, please submit on the wordpress.org forum. Thanks!

Description

Today I’m releasing Yet Another Related Posts Plugin (YARPP¹) 1.0 for WordPress. It’s the result of some tinkering with Peter Bowyer’s version of Alexander Malov & Mike Lu’s Related Entries plugin. Modifications made include:

1. Limiting by a threshold: Peter Bowyer did the great work of making the algorithm use mysql’s fulltext search score to identify related posts. But it currently just displayed, for example, the top 5 most “relevant” entries, even if some of them weren’t at all similar. Now you can set a threshold limit² for relevance, and you get more related posts if there are more related posts and less if there are less. Ha!
2. Being a better plugin citizen: now it doesn’t require the user to click some sketchy button to alter the database and enable a fulltext key. Using register_activation_hook, it does it automagically on plugin activation. Just install and go!
3. Miscellany: a nicer options screen, displaying the fulltext match score on output for admins, an option to allow related posts from the future, a couple bug fixes, etc.

Installation

Just put it in your /wp-content/plugins/ directory, activate, and then drop the related_posts function in your WP loop. Change any options in the Related Posts (YARPP) Options pane in Admin > Plugins.

You can override any options in an individual instance of related_posts using the following syntax:

`related_posts(limit, threshold, before title, after title, show excerpt, len, before excerpt, after excerpt, show pass posts, past only, show score);

Most of these should be self-explanatory. They’re also in the same order as the options on the YARPP Options pane.

Example: related_posts(10, null, 'title: ') changes the maximum related posts number to 10, keeps the default threshold from the Options pane, and adds title: to the beginning of every title.

There’s also a related_posts_exist) function. It has three optional arguments to override the defaults: a threshold, the past only boolean, and the show password-protected posts boolean.

Examples

For a barebones setup, just drop <?php related_posts(); ?> right after <?php the_content() ?>.

On my own blog I use the following code with <li> and </li> as the before/after entry options:

<?php if (related_posts_exist()): ?>
<p>Related posts:
<ol>
<?php related_posts(); ?>
</ol>
</p>
<?php else: ?>
<p>No related posts.</p>
<?php endif; ?>

Coming soon (probably)

1. Incorporation of tags and categories in the algorithm. I’ve gotten the code working, but I still need to think about what the most natural algorithm would be for weighing these factors against the mysql fulltext score currently used (and works pretty well, I must say).
2. Um, something else! Let me know if you have any suggestions for improvement. ^^

Version log

1.0 Initial upload (20071229)

1.0.1 Bugfix: 1.0 assumed you had Markdown installed (20070105)

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This blog post describes release 0.1… For the latest description, check out the WP-Smartdate plugin page or mitcho.com/code.

Please comment! I would love to hear your feedback on the plugin.

Description

WP-Smartdate looks for relative date expressions in your blog posts, such as “tomorrow,” “this coming Monday,” “last Friday,” and adds the date reference (like “2007-11-26”) as a machine-readable microformat.

Why Smartdate?

WP-Smartdate was created for three simple audiences:

1. For the machine: While many professional information retrieval algorithms go far beyond the scope of this program, smartdate helps the process along by adding machine-readable tags to relative date expressions.¹ In addition, these machine tags, in turn, help the human: a search on Google for “November 7th, 2007,” for example, will not pull up a document talking about “yesterday,” written on the 8th, but it will pull up the smartdate output of 2007-11-07.
2. For the human reader: Blog posts are often written in the “now,” using relative time expressions without concern for how the text will be read in the future. WP-Smartdate makes such posts easier to read and comprehend temporally².
3. For me: Because I think this sort of thing is fun!

A typology of smartdate date expressions

The following types of expressions are resolved with respect to the speech time—in WP-Smartdate’s case, the blog post date.

1. simple references: “yesterday,” “today,” “tomorrow,”
2. next/last DOTW expressions: “next Friday,” “this past Sunday,” “this Monday”

For the future

• static dates: “January 1st, 2007”
• duration shift expressions: “5 days ago,” “fourscore and seven years ago”
• day of the week shifts: “2 Fridays ago”
• clean up the code!

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