revers_product_list_by_category.py

    def product_list(self):
        products = self.products.all()
        product_list = []
        for product in products:
            for product_store in product.stores_for_product.all():
                product_list.append(product_store)

        for cat in self.child_categories.all():
            for product in cat.product_list():
                product_list.append(product)

        return product_list