I am trying to implement a discount code in which it would apply to a specific product but also a specific quantity of that product.For instance, a hat. The discount code applies to all hats but if the customer adds 2 hats to their cart, it would only apply to one, not both. Since the quantity would be limited to that product with a quantity of 1. Im trying to market a free items to drive some traffic to my site and am advertising a free hat with a given discount code, and it would apply to all hats. But I dont want to allow them to enter 50 hats and get them all for free. At the same time, I dont want to limit the card quality itself since I want to encourage them to shop for additional items.
I have looked into a couple of apps that you may be interested in for this particular feature. The app below may be slightly different to the current discount code process you're after but it can work well.
The first app is Gift Box - Free Gifts Purchase which will allow you to limit the quantity of a gift (in this case - a free hat) to 1 per cart. This does not put any limitations on the entire cart itself. Customers will need to either meet a certain price threshold, buy a product from a certain collection etc to receive the free gift. This strategy would also help customers look around the collections selected and add more items to cart.
It looks like you're on a roll with planning your marketing strategies. I would also like to advise you to look into having a strong social media strategy in place to help drive traffic to your website and have customers, not only take advantage of this great discount, but also make wider purchases across your site. We have a great blog on planning out your Social Media Strategy so check it out!