Common Validations

gistfile1.rb

# app/models/student.rb
class Student < ActiveRecord::Base
  include CommonValidations::StudentTeacherValidations
end

# app/models/teacher.rb
class Teacher < ActiveRecord::Base
  include CommonValidations::StudentTeacherValidations
end

# lib/common_validations/student_teacher_validations.rb
module CommonValidations
  module StudentTeacherValidations
    def self.included(klass)
      klass.validate :foo
    end
    
    def foo
      class_name = self.class.class_name
      errors.add("name", "must be the class name: #{class_name}") unless name == class_name
    end
  end
end