Adds the product’s Global Unique ID to both the regular order view and the order preview in the WooCommerce admin. Useful for stores or integrations that rely on unique product identifiers beyond SKUs.

add-global-id-to-admin-order-view.php

/**
 * Display Global ID (GTIN) in WooCommerce Order Admin
 * Works for both simple and variable products (variations)
 * 
 * @since 1.0.0
 */

// Display Global ID in regular order view (order details page)
add_action( 'woocommerce_after_order_itemmeta', function( $item_id, $item, $product ) {
    // Only show in admin and for line items
    if ( ! is_admin() || ! $item->is_type( 'line_item' ) ) {
        return;
    }
    
    // Get the product (for variable products, this returns the variation)
    $product = $item->get_product();
    
    if ( ! $product || ! method_exists( $product, 'get_global_unique_id' ) ) {
        return;
    }
    
    $unique_id = $product->get_global_unique_id();
    
    if ( $unique_id ) {
        echo '<div class="wc-order-item-global-id" style="color: #888; font-size: 12px; margin-top: 4px;">';
        echo '<strong>' . esc_html__( 'Global ID:', 'woocommerce' ) . '</strong> ' . esc_html( $unique_id );
        echo '</div>';
    }
}, 10, 3 );

// Filter the order preview HTML to add Global ID after SKU for each product
add_filter( 'woocommerce_admin_order_preview_get_order_details', function( $order_details, $order ) {
    // Get order items
    $line_items = $order->get_items();
    
    // Build a map of item_id => global_id (using item_id, not product_id)
    $item_global_ids = array();
    
    foreach ( $line_items as $item_id => $item ) {
        $product = $item->get_product();
        
        if ( ! $product || ! method_exists( $product, 'get_global_unique_id' ) ) {
            continue;
        }
        
        $unique_id = $product->get_global_unique_id();
        
        if ( $unique_id ) {
            $item_global_ids[ $item_id ] = $unique_id;
        }
    }
    
    // Only proceed if we found any Global IDs
    if ( empty( $item_global_ids ) ) {
        return $order_details;
    }
    
    $html = $order_details['item_html'];
    
    // For each item with a Global ID, find its specific row and add the Global ID
    foreach ( $item_global_ids as $item_id => $global_id ) {
        // Each item row has a unique class: wc-order-preview-table__item--{item_id}
        // Find the SKU div within this specific row and add Global ID after it
        $row_pattern = '/(<tr[^>]*wc-order-preview-table__item--' . preg_quote( $item_id, '/' ) . '[^>]*>.*?<div class="wc-order-item-sku">.*?<\/div>)/s';
        
        $global_id_div = '<div class="wc-order-item-global-id" style="color: #888; font-size: 12px;"><strong>Global ID:</strong> ' . esc_html( $global_id ) . '</div>';
        
        // Replace by adding Global ID div after the SKU div for this specific item
        $html = preg_replace(
            $row_pattern,
            '$1' . $global_id_div,
            $html,
            1 // Only replace once per item
        );
    }
    
    // Update the item HTML in the order details
    $order_details['item_html'] = $html;
    
    return $order_details;
}, 10, 2 );