Generating page specific classes in WordPress templates to keep code DRY and extensible

by / Filed under Web

How to generate page specific class names in a WordPress template, making it easy to extend your code and keep it DRY.

At work we use WordPress to run our main website. We’ve built a child theme that includes lots of custom templates so we can build non–standard of pages.

One such template is custom-hero.php. It calls the site header and displays the page excerpt on top of the custom image, should the page author have specified an excerpt and image in the WordPress page editor. You can see it in action on our Summer Reading Challenge page.

If you build a new page you’ll get some default styling. The hero image caption has a corporate purple background (#642D91) and is positioned in the bottom left of its containing div. The page title is centred and inherits the default heading font-weight.

Sometimes we might want to change these default styles. For example, we might build an event page which calls for a more muted approach, perhaps through a lighter heading font-weight, or a less garish caption background colour.

One way we could do this is by creating another WordPress custom template (custom-hero-tasteful.php, perhaps), but that’s obviously somewhat inefficient. Instead, we can go a bit more DRY and extend custom-hero.php’s classes.

Static and dynamic class names in WordPress templates

We want our template to spit out HTML with a static, default set of class names and something dynamically generated that’s unique to the page.

Take a look at the figcaption classes on the Summer Reading Challenge page for an example:

class="sl-hero-splash-text sl-hero-splash-text-summer-reading-challenge-2015"

We want all pages built on custom-hero.php to use the sl-hero-splash-text declarations, but only the Summer Reading Challenge page to use sl-hero-splash-text-summer-reading-challenge-2015

How do we do this in one WordPress template?

We basically need to spit out a piece of page specific text in our template. The most obvious page property that does this in a CSS friendly way (i.e. with no non–standard characters or spaces) is the page slug (summer-reading-challenge-2015 in our example). We can grab the post slug by querying the $post object:

global $post; echo $post->post_name;

So if we use this code in our custom-hero template we get static and dynamic class names:

<figcaption class="sl-hero-splash-text sl-hero-splash-text-<?php global $post; echo $post->post_name; ?>"><?php the_excerpt(); ?></figcaption>

By using dynamic class names we don’t have to write additional templates whenever we want to make minor styling changes. We make our code a lot more manageable.