WooCommerce WC()->session->set not working - wordpress

Question

I want to add some of the fields from a form into custom fields on a product so I can use them into an API call after payment is made. I have a redirection on my form that gets to the checkout page and add the product in the basket, code below:
<script>
document.addEventListener( 'wpcf7mailsent', function( event ) {
if (jQuery("input[type='checkbox'][name='try[]']").is(':checked')) {
location = 'http://www.thelittlegym.co.za/checkout/?add-to-cart=2506';
}
}, false );
</script>
Then, I have some code in my function.php to save the form data in the WC session.
I had to add declare the new session otherwise the set function didn't work.
If I do the init then I get an error saying "wc_empty_cart();" isn't defined (this function is from the WooCommerce plugin.
add_action('wpcf7_before_send_mail', 'send_form_data_to_wc_session', 5, 1);
function send_form_data_to_wc_session($contact_form) {
$submission = WPCF7_Submission::get_instance();
if($submission) {
$posted_data = $submission->get_posted_data();
if (!empty($posted_data['try'][0])) {
// Set data to WooCommerce session
WC()->session = new WC_Session_Handler();
// WC()->session->init();
WC()->session->set('cf7_posted_data', $posted_data);
}
}
}
Finally, I'm trying to retrieve the session data with the code below.
The var dump just returns NULL.
add_action('woocommerce_checkout_before_customer_details', 'wc_save_cf7_data_to_order', 10, 1);
function wc_save_cf7_data_to_order($order_id) {
$posted_data = WC()->session->get('cf7_posted_data');
var_dump($posted_data);
if(!empty($posted_data)) {
foreach($posted_data as $key => $data) {
echo '<b>', $key, ' : </b> ', $data, '<br />';
}
WC()->session->__unset('cf7_posted_data');
}
}
I believe the WC session set isn't working. I'm looking in the console for the Session Storage and can only see "wc_cart_hash_xxxxxxx", "wc_fragment_xxxxxxx" and "wc_cart_created".
Any idea how I can go ahead to debug this?

Answer 1

I've found an alternative solution on another topic, which solved my problem even if it doesn't explain why the code above didn't work.
add_action('wpcf7_before_send_mail', 'send_form_data_to_wc_session', 5, 1);
function send_form_data_to_wc_session($contact_form) {
$submission = WPCF7_Submission::get_instance();
if($submission) {
$posted_data = $submission->get_posted_data();
if (!empty($posted_data['try'][0])) {
// Set data to Session
session_start();//place this at the top of all code
$_SESSION['cf7_posted_data']=$posted_data;
}
}
}
and to retrieve:
add_action('woocommerce_checkout_before_customer_details', 'wc_save_cf7_data_to_order', 10, 1);
function wc_save_cf7_data_to_order($order_id) {
session_start();
$posted_data = $_SESSION['cf7_posted_data'];
var_dump($posted_data);
}