WordPress Custom Taxonomy Tree view

Result:

- taxonomy 1

- taxonomy 2

- - sub-taxonomy 2-1

- - sub-taxonomy 2-2

- taxonomy 3

function custom_taxonomy_tree_walker( $taxonomy, $parent = 0 ) {

    $terms = get_terms( $taxonomy, array( 'parent' => $parent, 'hide_empty' => false ) );

    if( count($terms) > 0 ) {

        $output = '<ul>';

        foreach ($terms as $term) {

            // function calls itself to display child elements, if any

            $output .= '<li><a href="' . get_term_link( $term ) . '">' . $term->name . '</a>' . custom_taxonomy_tree_walker($taxonomy, $term->term_id) . '</li>';

        }

        $output .= '</ul>';    

        return $output;

    }

    return false;

}



// usage

echo custom_taxonomy_tree_walker( 'custom_taxonomy_category' );