How To Change Your WordPress Category, Tag, or Post Format Permalink Structure

By January 10, 2014Tutorial

There are five default WordPress taxonomies: category, post_tag, post_format, nav_menu, and link_category – but nav_menu and link_category are off in a world of their own so let’s pretend they don’t exist for now. All of the settings for these taxonomies are preset by the fine folks at WordPress, and hard-coded into WordPress core, so if you want to make any changes, you have to do a little work.

The category, post_tag, and post_format default slugs, or permalinks, are simple. Categories are preceded by the slug ‘category’, post tags are preceded by the slug ‘tag’, and post formats are preceded by the slug ‘type’. In other words…

But what if you wanted to change the slug to something else? Or get rid of it altogether?

Changing the Slug

Changing the category/tag slug is pretty simple. The base for the slugs are stored as options so all you have to do is hook into the ‘pre_option_{option name}’ filter that’s applied when options are retrieved, allowing you to change the value that’s returned. The category slug’s option name is ‘category_base’ and the tag slug’s option name is ‘tag_base’ so the filters are ‘pre_option_category_base’ and ‘pre_option_tag_base’.

Changing the post format slug is a little different. The base is not stored as a option but it does have a filter: ‘post_format_rewrite_base’.

The following code will, most likely, go in your functions.php file. Remember that filters must always return a value. Learn more about filters.

add_filter( 'pre_option_category_base', 'mysite_change_category_base' );
function mysite_change_category_base( $value ) {
   
   // let's change our category slug to rantings
   // this will change the permalink to http://wpdreamer.com/rantings/wordpress/
   return 'rantings';

}

add_filter( 'pre_option_tag_base', 'mysite_change_tag_base' );
function mysite_change_tag_base( $value ) {
   
   // let's change our tag slug to ravings
   // this will change the permalink to http://wpdreamer.com/ravings/custom-post-types/
   return 'ravings';

}
add_filter( 'post_format_rewrite_base', 'mysite_change_post_format_base' );
function mysite_change_post_format_base( $value ) {
	
   // let's change our tag slug to fanciness
   // this will change the permalink to http://wpdreamer.com/fanciness/video/
   return 'fanciness';

}

Removing The Slug

Removing the slug altogether requires a different workaround, but it’s still pretty simple.

When WordPress registers these default taxonomies, the register_taxonomy() function adds a permastruct for each taxonomy that registers its permalink structure. All you need to do is overwrite the permastruct with your own.

These taxonomies and permastructs are registered during the ‘init’ action on priority level 0 (highest priority) so we’ll add our own hook into the ‘init’ action, but give it a lower priority so it’s executed after WordPress does its thing.

The following code will, most likely, go in your functions.php file. Learn more about actions.

Heads up: I don’t recommend removing the slug from categories, tags AND post formats. In fact, I wouldn’t recommend removing the slug from more than one of these taxonomies because then WordPress would have a very difficult time figuring out your URLs. The code for removing all three is only shown together so you can pick which set you need.

If you still want to remove multiple slugs, or if you’re having issues with your changes, I recommend installing the Rewrite Rules Inspector plugin. It shows you all of your rewrites and allows you to filter out which rewrites match a specific URL.


// make sure our action's priority is lower than 0,
// which is the highest priority, so basically any
// number greater than 0 will do. let's go with 1.
add_action( 'init', 'mysite_change_taxonomy_permalinks', 1 );
function mysite_change_taxonomy_permalinks() {

   // changing the category permastruct
   $taxonomy = 'category';
		
   // change the settings at will but make sure 'slug' is set to NULL
   $category_rewrite = array(
      'hierarchical' => true, // categories are defaulty hierarchical
      'slug' => NULL, // we don't want no slug!
      'with_front' => false, // this is up to you
      'ep_mask' => EP_CATEGORIES // this is a constant set by WordPress we'll use
      );
			
   // overwrites default category permastruct
   add_permastruct( $taxonomy, "%$taxonomy%", $category_rewrite );
		
   // ----------------------------------
		
   // changing the post_tag permastruct
   $taxonomy = 'post_tag';
		
   // change the settings at will but make sure 'slug' is set to NULL
   $post_tag_rewrite = array(
      'slug' => NULL, // we don't want no slug!
      'with_front' => false, // this is up to you
      'ep_mask' => EP_TAGS // this is a constant set by WordPress we'll use
      );
			
   // overwrites default post_tag permastruct
   add_permastruct( $taxonomy, "%$taxonomy%", $post_tag_rewrite );
			
   // ----------------------------------
		
   // changing the post_format permastruct
   $taxonomy = 'post_format';
		
   // change the settings at will but make sure 'slug' is set to NULL
   $post_format_rewrite = array(
      'slug' => NULL, // we don't want no slug!
      );
			
   // overwrites default post_format permastruct
   add_permastruct( $taxonomy, "%$taxonomy%", $post_format_rewrite );

}

Heads up: Sometimes messing with permalink settings requires you flush your system’s rewrite rules in order for the changes to take place. But they only need to be flushed once, each time you make a change, and not every time a page loads. To flush your rules, go to Settings -> Permalinks and click “Save Changes”.

About Rachel Carden

Rachel Carden is a High Ed Web Developer with a fondness for WordPress. She's also a puzzle fiend who gets way too excited about programming and problem solving. And you thought you were a nerd.