自从你开始悬赏以来，你没有回答任何评论。如果不知道您正在使用的设置是什么，以及与数据库相关的post元数据（注册的meta键）是什么，就没有人能够处理解决您的问题…
要根据不带任何插件的特定产品的项目数量获取特定自定义 checkout 计费字段的转发器，请执行以下操作：
1） 产品附加设置（激活此功能的复选框）：

// Display a custom setting option on product edit pages
add_action('woocommerce_product_options_general_product_data', 'add_product_repeater_checkbox_option');
function add_product_repeater_checkbox_option(){
    echo '<div class="product_custom_field">';

    // Custom Product Checkbox Field
    woocommerce_wp_checkbox( array(
        'id'          => '_qty_repeater',
        'label'       => __('Qty repeater', 'woocommerce'),
        'description' => __('Enable quantity repeater for additional "Name" and "Email" billing checkout fields', 'woocommerce'),
        'desc_tip'    => 'true'
    ));

    echo '</div>';
}

// Save the custom setting option value from product edit pages
add_action( 'woocommerce_admin_process_product_object', 'save_product_repeater_checkbox_option', 100, 1 );
function save_product_repeater_checkbox_option( $product ) {
    $qty_repeater = isset( $_POST['_qty_repeater'] ) ? 'yes' : 'no';
    $product->update_meta_data( '_qty_repeater', $qty_repeater );
}

2） 在 checkout 时添加/保存重复的附加字段（并标记顺序）：

add_filter('woocommerce_billing_fields', 'additional_billing_checkout_fields', 50, 1 );
function additional_billing_checkout_fields( $billing_fields ) {
    foreach(WC()->cart->get_cart() as $cart_item ){
        // Check if the "Quanty repeater option is set for the current item
        if( $cart_item['data']->get_meta('_qty_repeater') === 'yes' && is_checkout() && $cart_item['quantity'] > 1 ) {

            // Quantity repeater
            for( $i = 1, $j = 2; $i < $cart_item['quantity']; $i++, $j++ ){

                // Name fields
                $billing_fields['billing_name_person'.$j] = array(
                    'type'        => 'text',
                    'label'       => __("Name", "woocommerce") . ' ' . $j,
                    'class'       => array('form-row-first'),
                    'required'    => true,
                    'clear'       => false,
                );

                // Email fields
                $billing_fields['billing_email_person'.$j] = array(
                    'type'        => 'email',
                    'label'       => __("Email", "woocommerce") . ' ' . $j,
                    'class'       => array('form-row-last'),
                    'required'    => true,
                    'clear'       => true,
                );
            }
            break; // Only for one item
        }
    }
    return $billing_fields;
}

// Mark Order as having this additional fields data values
add_action('woocommerce_checkout_create_order', 'save_additional_billing_checkout_fields', 20, 2);
function save_additional_billing_checkout_fields( $order, $data ) {
    foreach( $order->get_items() as $item ){
        $product = $item->get_product();
        // Mark the order as containing additional fields
        if( $product->get_meta('_qty_repeater') === 'yes' && $item->get_quantity() > 1 ) {
            $item->update_meta_data( '_qty_repeater', '1' );
            break; // Stop the loop
        }
    }
}

3） 到处显示与数据相关的其他帐单字段（管理订单、订单视图、电子邮件）：

// Display additional billing fields values
add_action('woocommerce_order_details_after_order_table', 'display_additional_billing_fields_values' ); // Order received and view
add_action( 'woocommerce_email_after_order_table', 'display_additional_billing_fields_values' ); // Email notifications
add_action( 'woocommerce_admin_order_data_after_billing_address', 'display_additional_billing_fields_values' ); // Admin edit Order
function display_additional_billing_fields_values( $order ) {

    if( $order->get_meta('_qty_repeater') ) {
        // Only for email notifications
        if( ! ( is_wc_endpoint_url() || is_checkout() || is_admin() ) ){
            echo '<style>
            table.customer-details {width: 100%; font-family: \'Helvetica Neue\', Helvetica, Roboto, Arial, sans-serif;
                color: #737373; border: 1px solid #e4e4e4; margin-bottom:40px;}
            table.customer-details td{text-align: left; border-top-width: 4px; color: #737373; border: 1px solid #e4e4e4;
                padding: 12px; padding-bottom: 4px;}
            </style>';
        }
        // Others
        else {
            echo '<style> table.customer-details, table.customer-details td { border: none; } </style>';
        }

        echo '<h2>' . __( 'Customer details', 'woocommerce' ) . '</h2>';
        echo '<div><table class="customer-details" cellspacing="0">';

        // Loop through order items
        foreach( $order->get_items() as $item ){
            $product = $item->get_product();
            if( $product->get_meta('_qty_repeater') === 'yes' ) {
                // Loop through item quantity
                for( $i = 1, $j = 2; $i < $item->get_quantity(); $i++, $j++ ){
                    // Name
                    echo '<tr><td><strong>' . __("Name", "woocommerce") . ' ' . $j;
                    echo ': </strong>' . $order->get_meta('_billing_name_person'.$j) . '</td>';
                    // Email
                    echo '<td><strong>' . __("Email", "woocommerce") . ' ' . $j;
                    echo ': </strong>' . $order->get_meta('_billing_email_person'.$j) . '</td></tr>';
                }
                break;
            }
        }
        echo '</table></div>';
    }
}

4） 使其他帐单字段可编辑（管理员）：

add_filter( 'woocommerce_admin_billing_fields' , 'additional_admin_editable_billing_fields' );
function additional_admin_editable_billing_fields( $fields ) {
    global $pagenow, $post;

    if( $pagenow != 'post.php' ) return $fields;

    $order = wc_get_order($post->ID);

    if( $order->get_meta('_qty_repeater') ) {
        // Loop through order items
        foreach( $order->get_items() as $item ){
            $product = $item->get_product();
            if( $product->get_meta('_qty_repeater') === 'yes' ) {
                // Loop through item quantity
                for( $i = 1, $j = 2; $i < $item->get_quantity(); $i++, $j++ ){
                    $fields['name_person'.$j] = array(
                        'label'         => __("Name", "woocommerce") . ' ' . $j,
                        'show'          => false,
                        'wrapper_class' => 'first',
                    );
                    $fields['email_person'.$j] = array(
                        'label'         => __("Email", "woocommerce") . ' ' . $j,
                        'show'          => false,
                        'wrapper_class' => 'last',
                    );
                }
                break;
            }
        }
    }
    return $fields;
}

代码放在活动子主题（或活动主题）的function.php文件中。测试和工作。