如何检查复选框是否在 PHP 中被选中？

Question

我有一个表格，您可以选中该选项。

<div class="cr_woo_additional_group_group">
                <div class="cr_wp_clear"></div>
                <input type="checkbox" name="cr_woo_addional" id="vel_woo_additional_services_on" class="cr_woo_addional input-text qtyr text" value="">
                <p class="cr_woo_add_ser_desk"><?php echo $str; ?></p>
                <div class="cr_wp_clear"></div>
                <a href="javascript:void(0);" class="cr_woo_additional_group_trigger_close"><b>Отменить</b><i class="cr-icon wp-pandaclose" aria-hidden="true"></i></a>
            </div>

如果复选框被选中应该可以工作另一个代码。但是如果确认代码我有问题。怎么了？

function cr_woo_additional_services_selection( $cart_item_data, $product_id, $variation_id ) {

    if ( ! isset( $_POST[ 'cr_woo_addional' ] ) ) {
        $cart_item_data[ 'cr_woo_addional' ] = $_POST[ 'cr_woo_addional' ];
    }

    return $cart_item_data;
} 

和

if ( ! function_exists( 'cr_woo_additional_services_cart_item_name' ) ) {

    function cr_woo_additional_services_cart_item_name( $string, $order_item, $key ) {

        if ( ! empty( $order_item[ 'cr_woo_addional' ] ) ) {
            wp_enqueue_script( 'cr-woo-additional-services' );
            wp_enqueue_style( 'cr-woo-additional-services' );
            $string .= '<div class="cr-wp-hr"></div><i class="cr-icon wp-pandacut" aria-hidden="true"></i>Оверлок - ' . esc_attr( str_replace( 'м', '', $order_item[ 'cr_woo_addional' ] ) ) . ' м';
        }

        return $string;
    }
}