agenda-libre-ruby/app/controllers/regions_controller.rb

class RegionsController < InheritedResources::Base
  def stats
    @region_events = Event.joins(:related_region).group(:name).count(:name)

    @city_events = Event.group(:city).having('count(city) > 3').order('count(city) desc').count(:city)

    @month_events = Event
      .group('extract(year from start_time)')
      .group('extract(month from start_time)')
      .count()
  end
end