class PSPlacement{
    static transients = [
        "categoryHierarchy"
    }

    def String getCategoryHierarchy(){
        return this.getCategoriesForPlacement()?.join('>')
    }

   def  getCategoriesForPlacement(){
       if(category)
           return Category.executeQuery("SELECT ......")

       return []
    }

   static searchable = {

        all false
        categoryHierarchy index: "not_analyzed", name: "categoryHierarchy", store: "no"
        categoryHierarchy index: "not_analyzed", name: "categoryHierarchySort", store: "no"
    }
}