Hello Liberty Painting,

Thanks for reaching out to us.

Here is the script that you can try 

function my_custom_function($data) {
    $container = require AMELIA_PATH . '/src/Infrastructure/ContainerConfig/container.php';
    $customer = $data['bookings'][0]['customer'];
    // 'test test' is field value
    // 'note' is column name
    $container['domain.users.customers.repository']->updateFieldById($customer['id'], 'test test', 'note');
    return $data;
}
add_filter('AmeliaAppointmentBookingAddedFilter', 'my_custom_function', 10, 1);

Custom code needs to be applied to the page where the booking form is. Depending on what you're using (Gutenberg blocks, or some page builder), adding the CSS or JS can be done in a few different ways. 

If you need help with adding custom JS to the page, please take a look at this article.

Let us know if it works.

Hello Liberty Painting,

Apologies for the confusion, there was a misunderstanding. This script is for adding a customer note. You can try using this one instead 

function my_custom_function($data) {
    $container = require AMELIA_PATH . '/src/Infrastructure/ContainerConfig/container.php';
    $appointment = $data['appointment'];
    // 'test test' is field value
    // 'internalNotes' is column name
    $container['domain.booking.appointment.repository']->updateFieldById($appointment['id'], 'test test', 'internalNotes');
    return $data;
}
add_filter('AmeliaAppointmentBookingAddedFilter', 'my_custom_function', 10, 1);

Also, I've said that you need to add this as the JavaScript hook, but i see that you've already added it to the functions.php, and that is correct. Apologies for that.

It should be working now, please let us know.