wordpress form 7 custom tag and include mail with woo

php

<?php 

if( ! is_admin() ) {
    add_action( 'wpcf7_init', 'custom_add_form_tag_travel' );
     
    function custom_add_form_tag_travel() {
        wpcf7_add_form_tag( 'travel_name', 'custom_add_form_tag_travel_handler' ); 
    }
     
    function custom_add_form_tag_travel_handler( $tag ) {
        return get_travel_name();
    }
    
    // add_filter('wpcf7_special_mail_tags', 'wpcf7_tag_post', 10, 3);
    
    // function wpcf7_tag_post($output, $name, $html)
    // {
    //     $name = preg_replace('/^wpcf7\./', '_', $name);

    //     if ('travel-name' == $name) {
    //         return get_travel_name();
    //     }

    //     return $output;
    // }

    function get_travel_name(){
        global $woocommerce;
        $data;
        $items = $woocommerce->cart->get_cart();
        foreach($items as $item => $values) { 
            $_product =  wc_get_product( $values['data']->get_id()); 
            $data .= '<div id="currenttravelid">'.$_product->get_title().'</div>';
        }
        return $data;
    }
}

add_filter( 'woocommerce_add_to_cart_validation', 'remove_cart_item_before_add_to_cart', 20, 3 );
function remove_cart_item_before_add_to_cart( $passed, $product_id, $quantity ) {
    if( ! WC()->cart->is_empty() )
        WC()->cart->empty_cart();
    return $passed;
}