title: Get the Product ID from email templates in WooCommerce 3
body: <p>In Woocommerce I am trying to find out how to get the <strong>product id</strong> for a completed order inside the Customer completed order email template to store it as a PHP variable. This way I will be able to insert it into an external database. </p>
  
  <p>I already tried <code>$product-&gt;get_id();</code> but it does not work.</p>
  
  <p>How can get the Product ID in WooCommerce 3+ from email templates?</p>