Hiding the categories of a post when it is “uncategorized”

If you’ve ever had some posts on your WordPress blog, you will have noticed that the “Uncategorized” category is displayed with a link to an archive of uncategorized posts.

The easiest way to solve this, of course, is to categorize every blog post. But, if you don’t want to for some reason, you can use some PHP in your theme to hide the category of these posts. The example below is a customization I did for a theme in Bones but it should be easy to follow for other themes as well. The original line for the display of the categories in Bones is:

printf( __( 'filed under', 'bonestheme' ).': %1$s', get_the_category_list(', ') );

So, it is just using the WordPress function, get_the_category_list, to list a comma-separated list of categories for the post. How do we hide this if the post is uncategorized? Well, one way to do it is to get a list of categories for the post. If the number of categories is one, and that category is “Uncategorized” then we just won’t use the get_the_category_list display. Here is the code:

$show_categories = true;
$categories = wp_get_post_categories( $post->ID );
// We don't want to show the categories if there is a single category and it is "uncategorized"
if ( count( $categories ) == 1 && in_array( 1, $categories ) ) :
  $show_categories = false;
endif;
if ( has_category( null, $post->ID ) && $show_categories ) :
  echo ' & ' . __('filed under ', 'bonestheme') . get_the_category_list(', ');
endif;

We start off with the assumption that we’ll display the categories so we set a flag as true to begin with. Then, we retrieve the categories for a post. wp_get_post_categories will return the post’s categories as an array. Terms, or categories, for WordPress are stored in the wp_terms database table. And “Uncategorized” is actually a stored term with the term_id of 1:

With this knowledge, we check the number of categories of our post (retrieved with wp_get_post_categories) with a count call. If the result is one and the category array contains the “Uncategorized” category (term_id of 1) then we know we don’t have any categories we want to display. So, we’ll set our flag to false.

Finally, we make sure that the post does have categories and that our flag to display categories is set to true. WordPress’s has_category function, if given no category to check against, will just tell us if the post has any categories. If the post has categories and the flag is set to true, then we will use the category display line in our theme and display the post’s categories.