非常旧，但在搜索时仍会出现此问题，因此我将在我的文章中添加WooCommerce Customize Checkout Fields 以下是添加新签出字段的示例：

// Add a new checkout field
function kia_filter_checkout_fields($fields){
    $fields[\'extra_fields\'] = array(
            \'some_field\' => array(
                \'type\' => \'text\',
                \'required\'      => true,
                \'label\' => __( \'Some field\' )
                )
            );

    return $fields;
}
add_filter( \'woocommerce_checkout_fields\', \'kia_filter_checkout_fields\' );

// display the extra field on the checkout form
function kia_extra_checkout_fields(){ 

    $checkout = WC()->checkout(); ?>

    <div class="extra-fields">
    <h3><?php _e( \'Additional Fields\' ); ?></h3>

    <?php foreach ( $checkout->checkout_fields[\'extra_fields\'] as $key => $field ) : ?>

            <?php woocommerce_form_field( $key, $field, $checkout->get_value( $key ) ); ?>

        <?php endforeach; ?>
    </div>

<?php }
add_action( \'woocommerce_checkout_after_customer_details\' ,\'kia_extra_checkout_fields\' );

// save the extra field when checkout is processed
function kia_save_extra_checkout_fields( $order_id, $posted ){
    if( isset( $posted[\'some_field\'] ) ) {
        update_post_meta( $order_id, \'_some_field\', sanitize_text_field( $posted[\'some_field\'] ) );
    }
}
add_action( \'woocommerce_checkout_update_order_meta\', \'kia_save_extra_checkout_fields\', 10, 2 );

// display the extra data in the order admin panel
function kia_display_order_data_in_admin( $order ){  ?>
    <div class="order_data_column">
        <h4><?php _e( \'Extra Details\', \'woocommerce\' ); ?></h4>
        <?php 
            echo \'<p><strong>\' . __( \'Some field\' ) . \':</strong>\' . get_post_meta( $order->id, \'_some_field\', true ) . \'</p>\'; ?>
    </div>
<?php }
add_action( \'woocommerce_admin_order_data_after_order_details\', \'kia_display_order_data_in_admin\' );