shopping cart

My shop sells one product with one attribute.

The customer then adds the product several times but with different options for the attribute except for a few with same option value.

Just before he checks out, he will se a list of all the products in the shopping cart. I suppose the tpl_shopping_cart_default.php is responsible for that.
However where is the code which calculates the quantity based on selected option values?

Let us say that the cusomer buys t-shirts, 1 green, and 2 red.
I suppose the product_id will be the same for all tree t-shirts, but somehow zen can keep track on the quantity of red tshirts

You'll see different entries in your cart for the different attribute settings.

Scott

You might try the stock by attributes module available in the downloads section, Get the one by me mate kurio if using ZenCart 1.3.5 or later.