Greg Rickaby

Full-Stack Developer

· 2 min read · #code

Modify a Custom Post Type after it's been registered

Learn more about the filter to modify a Custom Post Type after it's been registered.

Today I was tasked with adding functionality to an existing custom post type. The problem was, the CPT was being registered in a plugin which I could not edit.

After some digging, I found there's a filter for that (found in post.php) which allows you to modify a custom post type, after it's been registered some other way.

apply_filters( 'register_post_type_args', $args, $post_type );

Hooking into that filter, allowed me to pass additional options to an existing CPT:

 * Filter the Products CPT to register more options.
 * @param $args       array    The original CPT args.
 * @param $post_type  string   The CPT slug.
 * @return array
function grd_client_filter_products_cpt( $args, $post_type ) {
 // If not Products CPT, bail.
 if ( 'products' !== $post_type ) {
  return $args;
 // Add additional Products CPT options.
 $products_args = array(
  'has_archive' => true,
  'supports'    => array( 'title', 'editor', 'author', 'thumbnail', 'excerpt', 'custom-fields', 'page-attributes' ),
 // Merge args together.
 return array_merge( $args, $product_args );
add_filter( 'register_post_type_args', 'grd_client_filter_products_cpt', 10, 2 );

Now "Products" has an archive, along with some other meta boxes in the post editor. Nice!

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