update-registered-taxonomy.php

update-registered-taxonomy.php

<?php

/**
 * Change `post_tag` to hierarchical example
 *
 * @author Everaldo Matias <https://everaldo.dev>
 * 
 * @see https://developer.wordpress.org/reference/hooks/init/
 * @see https://developer.wordpress.org/reference/functions/get_taxonomy/
 * @see https://developer.wordpress.org/reference/functions/register_taxonomy/
 */
function update_registered_taxonomy() {

    // get the arguments of the already-registered taxonomy
    $args = get_taxonomy( 'post_tag' ); // returns an object

    // make changes to the args
    $args->hierarchical = true;
    $args->rewrite['slug'] = 'people';

    // re-register the taxonomy
    register_taxonomy( 'post_tag', 'post', (array) $args );

}

add_action( 'init', 'update_registered_taxonomy', 99 );