Simple email validator for ActiveModel

email_validator.rb

# encoding: utf-8

class EmailValidator < ActiveModel::EachValidator

  # Validates that the specified attribute is a valid e-mail address
  #
  #   class Person < ActiveRecord::Base
  #     validates :email, :email => true
  #   end
  #
  # The validator expects that the e-mail not blank
  #
  # Configuration options:
  # * <tt>:message</tt> - A custom error message
  #
  # There is also a list of default options supported by every validator:
  # +:if+, +:unless+, +:on+ and +:strict+.
  # See <tt>ActiveModel::Validation#validates</tt> for more information

  def validate_each(record, attribute, value)

    # try to match and grab the entire value between @ and the end of the string
    # so "luis@gmail.com" should return "gmail.com"
    is_match = value.to_s.match(/\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\z/i)

    # if "is_match" is nil it's because the provided value is not a valid e-mail
    if is_match.nil?
      record.errors[attribute] << (options[:message] || :invalid)
    end
   
  end

end