I'm adding a categorization functionality to my app and struggling with it. Objects have many categories through categorizations. I'm trying to intercept the creation of a new categorization, check if theres a similar one, if so, increment it's count, if not, create a new object. Here's what I have so far. validate :check_unique protected def check_unique categorization = Categorization.where(:category_id => self.category_id, :categorizable_id => self.categorizable_id, :categorizable_type => self.categorizable_type) if categorization.first categorization.first.increment(:count) end end