I\'m trying to filter WooCommerce product archive by custom attributes.
For example, there are 5 products with attribute \"color\" containing \"red\", and another 3
You can use the WooCommerce Layered Nav widget, which allows you to use different sets of attributes as filters for products. Here's the "official" description:
Shows a custom attribute in a widget which lets you narrow down the list of products when viewing product categories.
If you look into plugins/woocommerce/widgets/widget-layered_nav.php, you can see the way it operates with the attributes in order to set filters. The URL then looks like this:
http://yoursite.com/shop/?filtering=1&filter_min-kvadratura=181&filter_max-kvadratura=108&filter_obem-ohlajdane=111
... and the digits are actually the id-s of the different attribute values, that you want to set.