Custom WooCommerce Plugin Development

Developing Custom WooCommerce Plugins

WooCommerce is built on WordPress hooks and provides its own hook layer on top — actions and filters for every stage of order, product, and payment lifecycle. Custom WooCommerce plugin is business logic not covered by standard WooCommerce or ready add-ons: specific pricing, internal ERP integration, non-standard discount types, custom order statuses. Medium complexity plugin development — 5–10 business days.

Basic Structure and Dependency Checking

<?php
/**
 * Plugin Name: My WooCommerce Extension
 * WC requires at least: 8.0
 * WC tested up to: 9.0
 */

defined('ABSPATH') || exit;

// Check WooCommerce presence before activation
register_activation_hook(__FILE__, function () {
    if (!class_exists('WooCommerce')) {
        deactivate_plugins(plugin_basename(__FILE__));
        wp_die('WooCommerce 8.0+ required');
    }
});

// Safe initialization after WooCommerce loads
add_action('woocommerce_loaded', function () {
    require_once plugin_dir_path(__FILE__) . 'includes/class-main.php';
    My_WC_Plugin::instance();
});

// Declare HPOS (High-Performance Order Storage) compatibility
add_action('before_woocommerce_init', function () {
    if (class_exists(\Automattic\WooCommerce\Utilities\FeaturesUtil::class)) {
        \Automattic\WooCommerce\Utilities\FeaturesUtil::declare_compatibility(
            'custom_order_tables',
            __FILE__,
            true
        );
    }
});

Custom Order Statuses

// Register status
add_action('init', function () {
    register_post_status('wc-awaiting-delivery', [
        'label'                     => 'Awaiting Delivery',
        'public'                    => true,
        'show_in_admin_status_list' => true,
        'show_in_admin_all_list'    => true,
        'exclude_from_search'       => false,
        'label_count'               => _n_noop(
            'Awaiting Delivery <span class="count">(%s)</span>',
            'Awaiting Delivery <span class="count">(%s)</span>'
        ),
    ]);
});

// Add to WooCommerce list
add_filter('wc_order_statuses', function (array $statuses): array {
    $statuses['wc-awaiting-delivery'] = 'Awaiting Delivery';
    return $statuses;
});

// Color in order list
add_filter('woocommerce_admin_order_statuses_list_badge', function (array $badges): array {
    $badges['awaiting-delivery'] = '#f59e0b'; // amber
    return $badges;
});

// Email on status change
add_action('woocommerce_order_status_awaiting-delivery', function (int $order_id): void {
    $order = wc_get_order($order_id);
    // send customer email
    WC()->mailer()->customer_new_account($order->get_billing_email());
});

Custom Discount System

Example: discount based on customer accumulated orders:

add_filter('woocommerce_cart_totals_coupon_label', '__return_false'); // hide standard coupon

add_action('woocommerce_cart_calculate_fees', function (WC_Cart $cart): void {
    if (is_admin() && !defined('DOING_AJAX')) return;

    $user_id = get_current_user_id();
    if (!$user_id) return;

    $total_spent = wc_get_customer_total_spent($user_id);
    $discount_pct = 0;

    if ($total_spent >= 100000) {
        $discount_pct = 10;
    } elseif ($total_spent >= 50000) {
        $discount_pct = 7;
    } elseif ($total_spent >= 20000) {
        $discount_pct = 5;
    }

    if ($discount_pct > 0) {
        $cart_subtotal = $cart->get_subtotal();
        $discount      = -($cart_subtotal * $discount_pct / 100);
        $cart->add_fee(
            sprintf('Accumulated discount %d%%', $discount_pct),
            $discount,
            true // taxable
        );
    }
});

Custom Product Fields

Add tab with fields in product editor:

// Add tab
add_filter('woocommerce_product_data_tabs', function (array $tabs): array {
    $tabs['production_info'] = [
        'label'  => 'Production',
        'target' => 'production_info_data',
        'class'  => ['show_if_simple', 'show_if_variable'],
        'priority' => 80,
    ];
    return $tabs;
});

// Tab content
add_action('woocommerce_product_data_panels', function (): void {
    global $thepostid;
    ?>
    <div id="production_info_data" class="panel woocommerce_options_panel">
        <?php
        woocommerce_wp_text_input([
            'id'          => '_manufacturer',
            'label'       => 'Manufacturer',
            'placeholder' => 'Company name',
            'value'       => get_post_meta($thepostid, '_manufacturer', true),
        ]);
        woocommerce_wp_select([
            'id'      => '_certification',
            'label'   => 'Certification',
            'options' => [
                ''       => 'Not specified',
                'gost'   => 'GOST',
                'iso'    => 'ISO 9001',
                'ce'     => 'CE',
            ],
            'value'   => get_post_meta($thepostid, '_certification', true),
        ]);
        ?>
    </div>
    <?php
});

// Save
add_action('woocommerce_process_product_meta', function (int $post_id): void {
    update_post_meta($post_id, '_manufacturer',  sanitize_text_field($_POST['_manufacturer'] ?? ''));
    update_post_meta($post_id, '_certification', sanitize_key($_POST['_certification'] ?? ''));
});

Background Tasks and Queues

For heavy operations (stock sync, bulk price updates) use WooCommerce Action Scheduler:

// Schedule task
as_schedule_single_action(
    time() + 60,
    'my_plugin_sync_stock',
    ['supplier_id' => 42],
    'my-plugin'
);

// Handler
add_action('my_plugin_sync_stock', function (int $supplier_id): void {
    $items = fetch_supplier_stock($supplier_id);
    foreach ($items as $sku => $qty) {
        $product_id = wc_get_product_id_by_sku($sku);
        if ($product_id) {
            $product = wc_get_product($product_id);
            $product->set_stock_quantity($qty);
            $product->save();
        }
    }
});

Action Scheduler is production-ready queue built into WooCommerce. Stores tasks in DB, retries on errors, has UI in /wp-admin → Tools → Scheduled Actions.

Typical timelines: plugin with custom product fields and statuses — 3–4 days. Plugin with custom discount logic, external API integration and background tasks — 8–12 days.