At least one product quantity field filled in

Hi,

I'm trying to create an order form, consisting of 137 products (it's a bakery's website). I added several dummy products in the form for testing purposes, but at least one product must have a quantity filled in. I can't make any single product required because not every customer would buy it. I just need to make sure people can't go to the next step without buying anything. Any ideas on how could I accomplish this? I guess I could try something with jQuery or something but I just want to know if there's any functionality like this built in already :)

Thank you in advance.

Thanks for the quick reply, David :) I've been doing some jQuery and unfortunately it's a little more complicated than I expected. Then again, I'm not much of an expert quite yet ;) I've tried to count a non-empty quantity field and throw out an alert when not a single field has any content, but for some reason the selector only applies to the first field. So if I enter a value in the first field, it works, but when I enter a value in any other after that it doesn't. Also tried to put a change event on the totals element but I couldn't get that to work either.

Bottomline: I'll gladly accept any push in the right direction :)