Changing a custom post type "has_archive" after registered

Question

Ok, I've seen some similar posts on how to change a custom post type's attributes after it has been registered (in my case, I'm trying to modify a custom post type created by a plugin without modifying the plugin files).

This appears to be working for some properties:

function change_wp_object() {
  $object = get_post_type_object('easy-rooms');
  $object->show_in_menu = true;
}
add_action('init','change_wp_object');

However, I can't seem to get has_archive to change - and it appears to be related to the permalinks. I'm guessing a new rule for /easy-rooms/ isn't being added.

I've tried adding flush_rewrite_rules() (even though it's a bad idea to run it at init) but even that doesn't work. Post type is set to public and if I do change the has_archive in the plugin code it does work.

Any ideas? Thanks in advance!

Answer 1

If Your WordPress installation is 4.4.0 or highter, you can filter the arguments pass to the register_post_type() function which is eventually pass to the WP_Post_Type::set_props

/**
 * Customize Your Post Type args after post type has been registered.
 * 
 * @param array  $args      Array of arguments for registering a post type.
 * @param string $post_type Post type key.
 * 
 * @return array
 */
function wpse_106784_filter_post_type_args( $args, $post_type ) {
    if ( 'your-custom-post-type' === $post_type ) {
        $args['show_in_menu'] = true;
        $args['has_archive'] = true;
        // any other args you need to cange
    }
    return $args;
}

add_filter( 'register_post_type_args', 'wpse_106784_filter_post_type_args', 10, 2 );

Edit:

Don't forget to update your permalink settings after adding the above snippet to your code. If it's a plugin and your plugin has install method (or activation hook) you can invoke flush_rewrite_rules() function there.

Sources:
https://developer.wordpress.org/reference/functions/register_post_type/#source https://developer.wordpress.org/reference/classes/wp_post_type/set_props/#source

Answer 2

Be sure 'rewrite' => true is set (to TRUE). Overlooked this converting a CPT without an archive to one with an archive.