Ticket #5034: category-slug-hierarchy.php

<?php
/*
Plugin Name: Category Slug Hierarchy
Plugin URI: http://smallvoid.com
Description: Fixes slugs for taxonomy with hierarchy (Ex. category)
Author: Rolf Kristensen
Version: 1.0
Author URI: http://smallvoid.com
*/

function fix_category_slug_hierarchy($q) {
        global $wp_rewrite;
        if ($wp_rewrite->using_permalinks() && $q->is_category)
        {
                foreach($q->query as $query)
                {
                        $slugs = explode('/', $query);
                        if (count($slugs) > 1)
                        {
                                $taxonomy = 'category';
                                $term;
                                foreach($slugs as $term_slug)
                                {
                                        if (isset($term))
                                        {
                                                $terms = get_terms($taxonomy, array('parent' => $term->term_id, 'slug' => $term_slug));
                                                $term = null;
                                                if (count($terms)==1)
                                                        $term = $terms[0];
                                                else
                                                        break;
                                        }
                                        else
                                        {
                                                $term = get_term_by('slug', $term_slug, $taxonomy);
                                        }
                                }
                
                                if (isset($term))
                                {
                                        $tax_query = array(
                                            array(
                                                'taxonomy' => $taxonomy,
                                                'terms' => $term->term_id,
                                                'field' => 'term_id',
                                            )
                                        );
                                        $tax_query = new WP_Tax_Query($tax_query);
                                        $q->tax_query = $tax_query;
                                }
                        }
                }
        }
}

if ( function_exists( 'add_filter' ) )
{
    add_action('parse_tax_query', 'fix_category_slug_hierarchy');
}
?>