A way of making map/reduce queries using a class

map_reduce.rb

module PageViewsByMonth
  def map
    <<-MAP
      function() {…}
    MAP
  end
  
  def reduce
    <<-REDUCE
      function() {…}
    REDUCE
  end
  
  def build
    Views.collection.map_reduce(map, reduce)
  end

  extend self
end

# Usage: PageViewsByMonth.build

I like this idea because it separates out the map and reduce quite nicely so you can see what is going on without muddling your models.