On the Edit Screen in the WP Admin there is a meta box for WP's built-in Category taxonomy. This meta box is built using post_categories_meta_box() (/wp-admin/includes/meta-boxes.php).

This meta box uses wp_popular_terms_checklist( $tax_name ) and wp_terms_checklist( $tax_name ) to output the actual categories (with checkboxes) within the meta box.

wp_terms_checklist() (wp-admin/includes/template.php) uses the Walker_Category_Checklist (/wp-admin/includes/class-walker-category.checklist) to build the categories/checkboxes.

Walker_Category_Checklist inherits from Walker (wp-includes/class-wp-walker.php) just like a number of other WP walkers (Walker_Nav_Menu, Walker_Comment, Walker_Category, etc.).

When extending the Walker_Nav_Menu we can hook into the wp_edit_nav_menu_walker filter and return our custom walker. Is there a way to do this with Walker_Category_Checklist?


Update 1:

I see in wp_terms_checklist() there is:

apply_filters( 'wp_terms_checklist_args', $args, $post_id );

I'm thinking that I can hook into this filter, change the walker argument to a custom walker and that this may do the trick?

  • So did my answer answer your question, or do you need further explanation, assistance or something else?
    – Sally CJ
    Commented Apr 29, 2021 at 21:36
  • 1
    Your answer was what I was looking for, thanks!
    – davemackey
    Commented May 3, 2021 at 1:59

1 Answer 1


Yes, as the documentation for wp_terms_checklist() stated, you can use the walker argument (which is part of the $args parameter for the wp_terms_checklist_args hook) to use a custom walker which modifies the output of the Category checklist generated by wp_terms_checklist(), e.g. the one in the "Categories" meta box on wp-admin/post.php.

Example where the custom walker is in a folder named includes:

add_filter( 'wp_terms_checklist_args', 'my_wp_terms_checklist_args', 10, 2 );
function my_wp_terms_checklist_args( $args, $post_id ) {
    require_once __DIR__ . '/includes/class-my-walker-category-checklist.php';

    $args['walker'] = new My_Walker_Category_Checklist;

    return $args;

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.