Save and display product selected custom data everywhere in WooCommerce

Question

I have a code that shows the checkbox on the product edit page. When I click on this checkbox, a select box is displayed on the single product page.

Here is my code:

Answer 1

Your checkbox value is stored to database, try to change this code

$roast_checkbox = isset( $_POST['_roast_checkbox'] ) ? 'yes' : 'no';

with

if ( isset( $_POST['_roast_checkbox'] ) {
$roast_checkbox = $_POST['_roast_checkbox'];
//update_post_meta
}