I am learning/working with RULES in my Drupal7 Commerce store. I thought this would be a fairly simple rule to create, but I can't find a work around for my need. I have a commerce site, that has our team uniforms. Each member is entitled to one and only one patch. If they add a second patch to their cart, I want a message to appear telling them that they can only have one patch in there cart and the add to cart process stopped.
So here is the scenario.
- Click the Add to Cart button for first patch, order/item/patch goes into cart
- Click the Add to Cart button for a second patch, message appears "you can't do that" and item does not go into cart
Where I am stuck is, what to select in the RULES UI, so it will check to see what is in the cart, look at the sku or item number [both of these are unique to the item], determine if the item that is to be added a duplicate, if so, pop up warning message, do not continue the process of adding that item.
Any help would be greatly appreciated.