woocommerce将自定义字段数据添加到$ package

Question

我正在通过以下代码在woocommerce购物车的结算部分创建自定义字段：

add_filter( 'woocommerce_default_address_fields', 'fts_cdek_fields_address' );


   function fts_cdek_fields_address($fields){

   $fields['cdek_city_id'] = array(

     'type'        => 'text',
     'label'       => __('Shipping city id. Technically needed.', $WCFCT),
     'placeholder' => '',
     'class'       => array( 'wc_fts_cdek_hide','update_totals_on_change','form-row-wide','address-field' ),
     'required'    => false,
     'clear'       => false,
     'label_class' => array( 'wc_fts_cdek_hide' )

   );

   return $fields;

   }

   function fts_cdek_fields_error(){

   // Check if thechnical field is clear => user didn't enter the city or entered it wrong! (Without cdek api and autocomplete)

   if(!isset($_POST['billing_cdek_city_id'])){

       wc_add_notice( __( 'Please reenter city in shipping area using autocomplete.' ), 'error' );

   }

   }

   add_action('woocommerce_checkout_update_order_meta', 'fts_cdek_fields_save');

   function fts_cdek_fields_save( $order_id ){

   if( !empty( $_POST['billing_cdek_city_id'] ) ){

       update_post_meta( $order_id, 'CDEK city ID', $_POST['billing_cdek_city_id'] );

       }

   }

我想在woocommerce自定义发货（calculate_shipping）中将我的字段值添加到$ package变量。如何在那里添加数据？