gistfile1.rb

class Classroom < ActiveRecord::Base
  belongs_to :school
  attr_accessible :code, :name, :school_id
  
  validates :code, :name, :school_id, :presence => true
  
  def school_name
    school.name
  end
  
  class << self
    ['code', 'name'].each do |type|
      define_method("#{type.pluralize}_by_school_id") do |school_id|
        Classroom.where(school_id: school_id).order(type).map(&(type.to_sym))
      end
    end
  end
end