title: Add custom field to cart item
body: <p>I am trying to add a custom field to each item that I am manually adding to the cart. The custom field is a print ID that is passed back from a third party API. </p>
  
  <p>This needs to be attached to each item in the cart so they can be used once the order has been paid for.</p>
  
  <p>I am trying setting the custom field for each cart item using $cart_item_data when manually adding to the cart. I am not sure if this is what I need to do but god loves a trier :)</p>
  
  <pre><code>$woocommerce-&gt;cart-&gt;add_to_cart( $product_id, 1, '', '', array(printJobId =&gt; 12345) );
  </code></pre>
  
  <p>When I view the order in woocommerce I cant see the printJobId anywhere.</p>
  
  <p>Does anyone know where I am going wrong?</p>
  
  <p>Thanks</p>