PHP Setup

Plugin Header

<?php
/**
 * Plugin Name: My WPA Addon
 * Description: Custom bookable type for WP Appointments.
 * Version: 1.0.0
 * Requires Plugins: wpappointments
 * Author: Your Name
 * Author URI: https://wppoland.com
 * License: GPL-2.0-or-later
 * Text Domain: my-wpa-addon
 */

declare(strict_types=1);

The Requires Plugins: wpappointments header ensures WordPress checks for the core plugin dependency.

Autoloading

Use Composer PSR-4 autoloading:

{
    "autoload": {
        "psr-4": {
            "MyAddon\\": "src/"
        }
    }
}

Dependency Check

Always check that WP Appointments is active before using its APIs:

add_action('plugins_loaded', function () {
    if (!class_exists('WPAppointments\Plugin')) {
        return;
    }

    // Safe to use WP Appointments APIs here
    require_once __DIR__ . '/vendor/autoload.php';

    // Register your bookable type, availability layers, etc.
});

Hooks for Extension

Hook	When to Use
init	Register bookable types and availability layers
plugins_loaded	Check dependencies, load autoloader
rest_api_init	Register additional REST endpoints
admin_enqueue_scripts	Enqueue addon admin assets