I am trying to add the parent category class in post_class() of some posts from one of my subcatgories. I have an advanved theme so I need to style all the posts from the parent cateogry using it's class, not the subcategory class (too much hassle in CSS).

2 Answers 2


Perhaps something like:

function mytheme_get_post_class_parent_cats() {
    $parent_cat_classes = array();
    // Get parent categories
    $post_cats = wp_get_post_categories();
    // Loop through post categories
    foreach ( $post_cats as $post_cat ) {
        $cat_parents = get_category_parents( $post_cat , false, ',', true );
        // if there are any parent categories
        if ( $cat_parents ) {
            // create an array
            $cat_array = explode( $cat_parents, ',' );
            // First key of the array is the top-level category parent
            $parent_cat_id = $cat_array[0];
            // Get the name of the top-level parent category
            $parent_cat = get_cat_name( $parent_cat_id );
            // create the CSS class .category-parent-{categoryname}
            $parent_cat_classes[] = 'category-parent-' . $parent_cat;
        } else {
            // Otherwise, the category is a top-level cat, so use it
            $cat_name = get_cat_name( $post_cat );
            $parent_cat_classes[] = 'category-parent-' . $cat_name;
    // Return CSS class, or false
    return $parent_cat_classes;

Then, when you call post_class():

<?php post_class( mytheme_get_post_class_parent_cats() ); ?>
  • There seems to be a problem with your function, it's not working o_O
    – rats
    Jul 17, 2011 at 21:19
  • It's example code for implementing the two referenced functions. Can you provide more detail? What's not working. Jul 17, 2011 at 21:22
  • as this is for a post, the function should loop through the post's categories: codex.wordpress.org/Function_Reference/wp_get_post_categories
    – Michael
    Jul 17, 2011 at 21:30
  • Okay, see updates. Added parameters to get_category_parents(), and added an explode() call to create the array from which to get the top-level parent category. Jul 17, 2011 at 21:31
  • Oh, good call, @michael! Let me adjust things a bit... Jul 17, 2011 at 21:34

A friend found the perfect solution, so I think it's fair to share it with you guys:

function rats_class($classes){
 global $post;
 return $classes;

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