WordPress Plugin Register Taxonomy for Object Type of Theme Taxonomies

Question

In my WordPress Plugin, I use the following code to automatically add Meta Boxes for all installed Taxonimies:

add_action( 'init', 'my_plugin_register_taxonomies_for_object_type');
function my_plugin_register_taxonomies_for_object_type()
{
  $args = array(
    'public'   => true,
  );
  $output = 'objects';
  $taxonomies = get_taxonomies( $args, $output );
  foreach  ( $taxonomies as $taxonomy )
  {
    register_taxonomy_for_object_type( $taxonomy->name, 'jt_condet_content' );
  }
}

This works really well for all Taxonmies, even those installed via plugins. However, I noticed that one Taxonomy is missing. It is a normal Post Taxonomy installed by a Child Theme using register_taxonomy() in the init hook of the Theme.

Any idea why only this Taxonomy is missed by my plugins my_plugin_register_taxonomies_for_object_type()? It drives me crazy. I want to show meta boxes for all installed public Taxonomies, no matter if they are build in, installed via a Plugins or via a Themes.

I played around a little bit with the action hook and wp_loaded seems to work but i'm not 100% confident that this is the right hook to use or am I fine?

Can you explain me the downsided of using wp_loaded over init?

Answer 1

If you're using init and the child theme is also using init you probably just need to change the priority of your hook to ensure it runs after theirs. Try doing:

add_action( 'init', 'my_plugin_register_taxonomies_for_object_type', 20 );

Assuming their theme uses the default (10) yours will run after theirs and their taxonomy should be available.

The only downside I can think for using wp_loaded is that wp_loaded will run after a few other actions such as widgets_init, register_sidebar and probably a few others. If there are any other callbacks by other plugins / themes that would expect your post type to have these taxonomies registered, and they hook before wp_loaded, they'd fail because wp_loaded runs after them. It's likely wp_loaded would be fine in most cases.