我在WooCommerce签出中添加了一个自定义字段，如下所示：

function oc_add_checkout_fields( $fields ) {
    $fields[\'shipping_sub_area\'] = array(
        \'label\'    => __( \'Sub Area\' ),
        \'type\'     => \'select\',
        \'class\'    => array( \'form-row-wide\', \'update_totals_on_change\' ),
        \'priority\' => 68,
        \'required\' => true,
        \'id\'       => \'th_sub_area\',
        \'options\'  => array(
            \'\'        =>\'Select\',
            \'Clifton\' => \'Clifton1\', 
            \'DHA\'     => \'DHA1\',
        ),
        \'custom_attributes\' => array(),
        \'validate\'          => array(),
        \'default\'           => \'\',
    );

    return $fields;
}
add_filter( \'woocommerce_default_address_fields\', \'oc_add_checkout_fields\' );

更改此字段后，签出表单中的“您的订单”部分会显示预加载程序。我想执行以下操作：如果上述字段中的选定值为Clifton1，则将运费100添加到购物车，否则将运费300添加到购物车，

我尝试了不同的钩子和操作，但无法获得钩子中自定义添加字段的值。例如，我使用了以下过滤器：

function filter_woocommerce_cart_shipping_packages( $array ) { 
    // make filter magic happen here... 
    //die(\'I am hre\');
    echo \'<pre>\';
    print_r($array);
    return $array; 
}; 

// add the filter 
add_filter( \'woocommerce_cart_shipping_packages\', \'filter_woocommerce_cart_shipping_packages\', 10, 1 ); 

在中$array, 我得到：

[destination] => Array
    (
        [country] => PK
        [state] => TA
        [postcode] => 
        [city] => fds
        [address] => fsdf
        [address_1] => fsdf
        [address_2] => fsd
    )

但我没有得到shipping_sub_area 或th_sub_area.

/*Ajax Call Back*/
add_action( \'wp_ajax_my_action\', \'my_action_callback\' );

$shipping_charges;
function my_action_callback() {
    $shipping_charges =  $_POST[\'shipping_charges\'];
    WC()->session->set("th_shipping_charges", $shipping_charges );
}

/*Ajax code to get values from the form and post to Wordpress backend*/

add_action( \'wp_footer\', \'my_footer_code\' );

function my_footer_code() { 
$html=\'
    jQuery("#th_sub_area").change(function(){
    var shipping_charges;
        var selected_sub_area = jQuery("#th_sub_area").find(":selected").val();
        if(selected_sub_area=\'DHA\'){
               var shipping_charges= 150; 
        }

       / In front end of WordPress we have to define ajaxurl /  
       var ajaxurl = "\'.admin_url(\'admin-ajax.php\').\'";

       var data = {
         "action": "my_action",
       "shipping_charges" : shipping_charges,
                };

                jQuery.post(ajaxurl, data, function(response) {
                    jQuery("body").trigger("update_checkout");
                });
    });
\';
echo $html;
}