Custom post types - Use post_id in permalink structure when using has_archive => true

Question

I recently asked this question Custom post types - Use post_id in permalink structure and solved it but as I have enabled 'has_archive' => true the solution given no longer works. Let me explain:

I'm after this structure:

• archive-events.php => /news/events/
• single-events.php => /news/events/%post_id%/%postname%

To get post_id in a single event permalink I've had to add %post_id% to the CPT slug but when enabling has_archive => true the archive page becomes the slug; in this case becoming /news/events/%post_id%/ which is invalid.

So my question:

How do I have post_id in permalink structure when using has_archive => true

Answer 1

To get what you need you have to add a custom rewrite rule and to filter the permalink construction. The following code does both:

<?php # -*- coding: utf-8 -*-
/**
 * Plugin Name: Event Permalinks
 */
// Not a WordPress context? Stop.
! defined( 'ABSPATH' ) and exit;

// Wait until all needed functions are loaded.
add_action( 'init', array ( 'Bradys_Events', 'init' ) );

class Bradys_Events
{
    /**
     * Creates a new instance.
     * 
     * @wp-hook init
     * @see    __construct()
     * @return void
     */
    public static function init()
    {
        new self;
    }

    /**
     * Constructor
     */
    public function __construct()
    {
        $args = array(
            'label' => 'events',
            'public' => true,
            'hierarchical' => false,
            'has_archive' => true,
            'rewrite' => array(
                'with_front' => false,
                'slug' => "news/events"
            ),
            'supports' => array( 'title', 'editor', 'thumbnail' )
        );
        register_post_type("events", $args);

        // Prevent WordPress from sending a 404 for our new perma structure.
        add_rewrite_rule(
        '^news/events/(\d+)/[^/]+/?$',
        'index.php?post_type=events&p=$matches[1]',
        'top'
        );

        // Inject our custom structure.
        add_filter( 'post_type_link', array ( $this, 'fix_permalink' ), 1, 2 );
    }

    /**
     * Filter permalink construction.
     * 
     * @wp-hook post_type_link
     * @param  string $post_link default link.
     * @param  int    $id Post ID
     * @return string
     */
    public function fix_permalink( $post_link, $id = 0 )
    {
        $post = &get_post($id);
        if ( is_wp_error($post) || $post->post_type != 'events' )
        {
            return $post_link;
        }
        // preview
        empty ( $post->slug )
            and $post->slug = sanitize_title_with_dashes( $post->post_title );

        return home_url(
            user_trailingslashit( "news/events/$post->ID/$post->slug" )
        );
    }
}

Visit wp-admin/options-permalink.php one time to let WordPress update its rewrite rules.