Ukázky kódu.

validates_length_of :title, :maximum => 12, :message => 'Titul je příliš dlouhý - maximálně 12 znaků'

ActiveRecord::Validations:

    protected
      def validate
        errors.add_on_empty %w( first_name last_name )
        errors.add("phone_number", "has invalid format") unless phone_number =~ /[0-9]*/
      end

      def validate_on_create # is only run the first time a new object is saved
        unless valid_discount?(membership_discount)
          errors.add("membership_discount", "has expired")
        end
      end

      def validate_on_update
        errors.add_to_base("No changes have occurred") if unchanged_attributes?
      end