A conditional tag can make the browsing experience for your visitors a little different depending on which page they are browsing. I use conditional tags extensively on this website. How do you think I get the list of all previous tutorials I’ve written listed on only the tutorial pages? How is it the recent post listings display on the sidebar on every page, except the homepage? This is all through conditional tags. In this tutorial I’ll go over:

• What exactly a conditional tag is
• A list of the WP conditional tags and what their functions are
• How to put a conditional tag to use while avoiding errors
• Real examples of conditional tags used in WordPress themes

To learn everything you need to know about conditional tags and how it relates to WordPress themes, read on…

Warning: This tutorial has a lot of code and examples. Please press the back button if code makes you uneasy.

What are conditional tags and what can they be used for

Conditional tags are a very important part of your WordPress theme coding repertoire. They perform a similar role compared to the template hierarchy, which we went over briefly in the previous ultimate guide on the WordPress loop. Basically these quick snippets of PHP code can make your theme do something based on the type of WordPress page you’re on.

List of conditional tags and their functions

is_home() This is for use on the main blog page, usually your home page.
is_front_page() *WordPress 2.5 Only* If you’re using a static front page (not the standard latest blog posts) this is the conditional tag to be used.
is_single() To be used on single blog post pages.

is_single('1') Where 1 is the post ID.
is_single('hello-world') Where hello-world is the post slug
is_single('Hello World!') Where Hello World! is the post title

is_page() For WordPress pages.

is_page('2') Where 2 is the page ID.
is_page('about') Where about is the page slug
is_single('About Me') Where About Me is the page title

is_category() - When a category page is listed, similar arguments as the is_single() and is_page()
in_category('1') - When a post is in category ID 1.
is_tag() - On a tag archive page, similar to is_category().
is_archive() Any archive page including monthly, categories, and tags.
is_search() For search results pages.
is_404() When a page is not found

A complete list is provided on the WordPress Codex.

How to use WordPress conditional tags

If you know PHP, this part will be a breeze for you. If not, may be slightly more difficult - but I’ll be providing all the code and concepts you need so it won’t be too hard to understand. Let’s say you wanted to display a little welcome message for your visitors that’s only displayed on the home page.

For our example, we’ll use a freshly installed WordPress 2.5 with the default Kubrick theme. Let’s open up sidebar.php the theme editor. Hopefully your theme is writable before doing this.

Right after the sidebar div begins (<div id=”sidebar”>) we’ll place the following code:

<?php if (is_home()) { ?>
<p>Welcome blog visitor, perhaps you would like to subscribe to my feed? This message will only be displayed on the homepage.</p>
<?php } ?>

Just to clarify the code itself and it’s placement, here’s a screenshot of what it should look like in the theme editor:

The conditional tag is used with an php if statement so therefore uses php tags. Notice the brackets, and how the php tag closes when there’s straight HTML displayed. Also notice how the PHP tag opens again to have a closing bracket. This is very important, as forgetting this will cause the entire page below to break with an error.

Now, let’s open up the test blog homepage in a web browser.

As you can see, that little message we placed in the sidebar is displayed in the sidebar on the homepage. It will not be visible on any other page of the site.

More examples of conditional tags in use

Okay, I know that was a pretty boring example, but hopefully you have the basic hang of it now.

Sidebar Manipulation

A lot of examples are actually present in the same sidebar.php file of the default theme. Let’s take a look at the following example in that:

<?php /* If this is the frontpage */ if ( is_home() || is_page() ) { ?>
<?php wp_list_bookmarks(); ?>
<li><h2>Meta</h2>
<ul>
<?php wp_register(); ?>
<li><?php wp_loginout(); ?></li>
<li><a href="http://validator.w3.org/check/referer" title="This page validates as XHTML 1.0 Transitional">Valid <abbr title="eXtensible HyperText Markup Language">XHTML</abbr></a></li>
<li><a href="http://gmpg.org/xfn/"><abbr title="XHTML Friends Network">XFN</abbr></a></li>
<li><a href="http://wordpress.org/" title="Powered by WordPress, state-of-the-art semantic personal publishing platform.">WordPress</a></li>
<?php wp_meta(); ?>
</ul>
</li>
<?php } ?>

This code will display your blogroll and meta items on the sidebar of the homepage and single pages only - not on any archive pages, author pages, 404 pages, etc. What those two lines together ( the || between the two conditionals) do is act as a logical OR function. Basically it’s saying - if the page you’re on is the homepage or a single page, display what’s inside the brackets.

How to get something to show up on all pages except…

In the opening paragraph of this article, I mentioned how I get recent post articles to display on every page, except the homepage. Here’s a little code hack that will allow you to do this, taken straight from my sidebar.

<?php if (is_home()) { } else { ?>
<h2 id="recentposts">Recent Posts</h2>
<div class="cont">
<ul>
<?php wp_get_archives('title_li=&type=postbypost&limit=10'); ?>
</ul>
</div>
<?php } ?>

Basically this code is saying: if on the homepage, do nothing - else display the recent posts.

Why would I want to do this? Probably because you can already see the latest posts when you’re on the homepage, why have another list of the exact same thing? Please note you may not need that extra CSS formatting because like I said, this code was taken directly from my sidebar - my template.

Conditional Tags in other places

On the Pushing Borders theme, I used conditional tags to display a different heading corresponding to the type of page a user was on. If you download and look at the header.php file, you’ll see the following in the header div.

<big><?php if (is_home()) { echo "home"; } elseif (is_single()) { echo "blog"; } elseif (is_page()) { echo "page"; } elseif (is_search()) { echo "search"; } elseif (is_archive()) { echo "archive"; } ?></big>

Instead of making separate little if statements, I incorporated this into one big if elseif statement encompassing all the major conditional tags into one. Make sure you use proper syntax or you will run into errors. This Elseif tutorial from Tizag.com does a good job of explaining the PHP aspect of things.

Conclusion

Conditional tags can be a very powerful thing. Be creative with it. The possibilities certainly aren’t limited to the examples here. Check out what other blogs do with their sidebars and take note of changes on different types of pages to get ideas.

Hope you enjoyed the guide. Feel free to comment and share if you liked it. Subscribe to the feed to get all the latest theme release and tutorial updates.