I've been searching around for a way to add a message to the tag metabox before the input data-wp-taxonomy. When searching under the tags and but I was only able to populate fourteen results.

When I research the core for data-wp-taxonomy I found the meta-boxes.php file and the function for post_tags_meta_box which led me to How to Add Reminders/Notes to New Post Meta Boxes but that question is over five years old and ties into it with jQuery:

function load_my_alerts(){
        get_template_directory_uri() . '/js/alerts.js', 
        array( 'jquery' )
    wp_enqueue_script( 'my_alerts' );
add_action('admin_enqueue_scripts', 'load_my_alerts');

Is there another way to add a message before the input on the tag metabox?

1 Answer 1


Here's a workaround specific for the post tags meta box.

We can register a custom metabox callback for the post_tag taxonomy with:

add_filter( 'register_taxonomy_args', function( $args, $taxonomy )
    // Replace the original (post_tag) metabox callback with our wrapper
    if( 'post_tag' === $taxonomy )
        $args['meta_box_cb'] = 'wpse_post_tags_meta_box';

    return $args;

}, 10, 2 );

where our custom callback is e.g.:

function wpse_post_tags_meta_box( $post, $box )
    // Custom action
    do_action( 'wpse_before_post_tags_meta_box', $post, $box );

    // Original callback. Note it will echo the stuff, not return it
    post_tags_meta_box( $post, $box );

Now we can hook into the custom wpse_before_post_tags_meta_box hook when needed.

If we need to inject something inside the post_tags_meta_box() function, then we might try using output buffering to work with it as a string. It's also possible to duplicate that function, but that function could easily change in the future! So I would avoid that if possible.

  • I was just looking into post_tags_meta_box to figure something like this. Can we filter every function in the core? Even if it's not being filtered already?
    – Johansson
    Jun 22, 2017 at 16:18
  • I guess there are different ways around this, so please share what you come up with. I wasn't sure if I should post this on the other linked question, but that question sounded more general for all metaboxes. So I posted it here instead. In theory one could use output buffering on the whole page and replace anything we want, but that's totally over the top ;-) Sometimes it's better to limit the scope a little bit more than that and use hooks/api if they are available for the job.
    – birgire
    Jun 22, 2017 at 16:24
  • Well i was just wondering if we can directly filter the post_tags_meta_box( $post, $box ); and pass our own arguments. Is it possible?
    – Johansson
    Jun 22, 2017 at 16:26
  • I didn't find any explicit filters for post_tags_meta_box() and it uses echo's instead of return,. So I Ijust registered a wrapper instead, with modifications, that also calls the original post_tags_meta_box() callback.
    – birgire
    Jun 22, 2017 at 16:31
  • Yes I heard in the chatroom that the function is going to be merged with category list. Thanks!
    – Johansson
    Jun 22, 2017 at 16:42

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