gistfile1.rb

require 'active_support/ordered_hash'
require 'active_support/core_ext/enumerable'

module Enumerable
  def group_by_attribute(attr, options={:nils_first => true})
    raise "attr parameter must by a symbol" unless attr.is_a?(Symbol)
    h = group_by(&attr)
    returning h2 = ActiveSupport::OrderedHash.new do
      h2[nil] = h.delete(nil) if options[:nils_first] && h.has_key?(nil)
      h2.merge!(h)
    end
  end unless [].respond_to?(:group_by_attribute)
end

class NewsItem  < ActiveRecord::Base

  # ... Lots of stuff omitted for brevity

  def self.all_grouped_by_feed
    self.all.group_by_attribute(:feed_id)
  end
end