Remove post type slug from WordPress custom types

remove-cpt-slug.php

<?php

namespace RyanSechrest\Plugin;

/**
 *  Plugin Name: Remove CPT Slug
 *  Version: 1.0
 *  Author: Ryan Sechrest
 *  Author URI: http://ryansechrest.com/
 *  Description: Remove custom post type slug from URLs.
 *  License: GPL2
 */

// Create shortcut for namespace
if (!defined(__NAMESPACE__ . '\NS')) {
    define(__NAMESPACE__ . '\NS', __NAMESPACE__ . '\\');
}

// Create shortcut for plugin slug
if (!defined(NS . 'PS')) {
    define(NS . 'PS', 'remove-cpt-slug');
}

/******************************************************************************/

add_action(
    'init',
    NS . 'initialize_plugin'
);

function initialize_plugin() {
    register_post_type_service();
    hook_post_type_link();
    hook_pre_get_posts();
}

/******************************************************************************/

function register_post_type_service() {
    $label = __('Services', PS);
    $labels = array(
        'name'               => __('Services', PS),
        'singular_name'      => __('Service', PS),
        'menu_name'          => __('Services', PS),
        'all_items'          => __('All Services', PS),
        'add_new'            => __('Add Service', PS),
        'add_new_item'       => __('Add New Service', PS),
        'edit_item'          => __('Edit Service', PS),
        'new_item'           => __('New Service', PS),
        'view_item'          => __('View Service', PS),
        'search_items'       => __('Search Services', PS),
        'not_found'          => __('No services found', PS),
        'not_found_in_trash' => __('No services found in trash', PS),
        'parent_item_colon'  => __('Parent Service', PS)
    );
    $description = __('Services', PS);
    $supports = array(
        'title',
        'editor',
        'page-attributes'
    );
    $taxonomies = array();
    $arguments = array(
        'label'         => $label,
        'labels'        => $labels,
        'description'   => $description,
        'public'        => true,
        'show_ui'       => true,
        'menu_position' => 20,
        'hierarchical'  => true,
        'supports'      => $supports,
        'taxonomies'    => $taxonomies,
        'has_archive'   => false,
        'rewrite'       => true,
        'query_var'     => true,
        'can_export'    => false
    );
    register_post_type('service', $arguments);
}

/******************************************************************************/

function hook_post_type_link() {
    add_filter(
        'post_type_link',
        NS . 'post_type_link',
        10,
        3
    );
}

function post_type_link($permalink, $post, $leavename) {

    // Remove post type slug from these post types
    $post_types = ['service'];

    // If current post doesn't have post type listed above
    if(!in_array($post->post_type, $post_types)) {

        return $permalink;
    }

    // Remove post type slug from permalink
    $permalink = str_replace($post->post_type . '/', '', $permalink);

    return $permalink;
}

/*************************************************************************/

function hook_pre_get_posts() {
    add_action(
        'pre_get_posts',
        NS . 'pre_get_posts'
    );
}

function pre_get_posts($query) {
    global $wpdb;

    // If current query is WordPress' main query
    if (!$query->is_main_query()) {
        return;
    }

    // Get page name from query
    $post_name = $page_name = $query->get('pagename');

    // Determine if post name contains slash
    $last_pos = strrpos($post_name, '/');

    // If post name contains slash, it's hierarchical
    if ($last_pos !== false) {

        // Extract actual post name
        $post_name = substr($post_name, $last_pos + 1);
    }

    // Retrieve post type based on post name
    $post_type = $wpdb->get_var(
        $wpdb->prepare(
            'SELECT post_type FROM ' . $wpdb->posts . ' WHERE post_name = %s LIMIT 1',
            $post_name
        )
    );

    // Only process specified post types
    switch ($post_type) {
        case 'service':
            $query->set('service', $page_name);
            $query->set('post_type', $post_type);
            $query->is_single = true;
            $query->is_page = false;
            break;
    }

    return $query;
}