Scope nested model with ancestry gem

I use two models:

Productgroup (has_ancestry has_many products)

Product (belongs_to productgroup)

The product model is using the attribute "active".

Now I would like to scope the Productgroup model to get only productgroups with active products. There may be root productgroups with no products but with childs that have active products. So I'm looking for something like this:

@productgroups = Productgroup.includes(:products).where("productgroups.children.products.active IS ?", true)

Does anyone has an idea how to do this?