I need to show a text area custom field inside the checkout>details just if the order contains a product with a certain category ID. How to do it?
this is the scenario: for example, in my store i sell prints and illustrations. (prints are shipped by post and illustrations are downlodable only) if the details page (next step after checkout) contains an illustration (category_id XX) I want to show a text area where customer write down all specs, instructions and comments.
for other products, prints and other common items i don't want to show this custom field inside the checkout page
Please advice me! thank you ;)