active_sample.rb

class ActiveRecord::Base
  def self.sample(n = 1)
    case n <=> 1
    when -1
      puts "don't be a shit"
      nil
    when 0
      chosen_rand = rand(self.count) + 1
      self.find(chosen_rand)
    when 1
      record_count = self.count
      records = Set.new
      until records.count == n
        chosen_rand = rand(record_count) + 1
        user = self.find(chosen_rand)
        records.add(user) unless records.include?(user)
      end
      records
    end
  end
end