From: Christopher Dicely Date: 2008-02-16T16:28:35+09:00 Subject: Re: collection sum This sounds like a Rails question, and you may want to ask it on a Rails-specific list; also, its hard to tell what may be going on without knowing the definition of the objects being used. With the most intuitive layout of objects for what you seem to be doing, I'd expect what you are looking for to be something like current_user.carts.first.items.sum(:unit_price). On Feb 15, 2008 6:55 PM, Grayson Piercee wrote: > Hello, > > I really like the ability to do sums right in the object model, for > example > > @items.sum(:unit_price), etc! works great! > > However I wonder how you step down through an association to do a sum > > current_user.carts.first.cart_items.items.sum(:unit_price) > > Finding the users first cart works fine but the collection to collection > between cart_items to items doesn't. > > TIA > > GP > -- > Posted via http://www.ruby-forum.com/. > >