Abstract Factories along with ActiveRecord
How to extract SQL aggregations into abstract factories keeping your model clean.
Pattern description and discussion.
I just encountered and solved an interesting problem that I'd like to discuss in a talk next meetup if someone's interested. I ended up with a beautiful solution, imho.
The problem appeared in a statistics timeline apllication and there's ruby code to show. ;) I didn't find anything comparable on the interwebs, so I'd like to present my solution and discuss it with the audience.