How can I get the product count of a category subject to the current facet?

Question

For reasons I will not go into (inheriting an old code base), I need to find the product count of a specific category subject to the current facet.

Say I am on the category page, and I have loaded a list of child categories. I would like to find the product count for each sub-category based upon the current facet selections. All of this needs to be done without using the standard facet nav implementation.

Answer 1

So you have the categories collection $categories and current facet selection in the $layer object.

Then you can just call do

$layer->getProductCollection()
      ->addCountToCategories($categories);

and then get the counts like

        foreach ($categories as $category) {
            echo $category->getProductCount()) {
        }