#!/usr/bin/env ruby
 
require "active_model"
require "active_support/core_ext"

# Checks a value not equals to another attribute's one.
#
#     validates :password, not_equals_to: :login
#
# Use the <tt>:allow_nil</tt> key to skip validation in case the attribute value isn't set.
#
#     validates :password, not_equals_to: :login, allow_nil: true
#
class NotEqualsValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    return if value.nil? && options[:allow_nil]
    if value == record.send(options[:to])
      record.errors.add attribute, :not_equals
    end
  end
end