user_auth.rb

class User < ActiveRecord::Base
  require 'digest/md5'

  validates_presence_of :email, :password
  
  def self.authenticate(email, password)
    User.find_by_email_and_password(email, Digest::MD5.hexdigest(password))
  end

  def password=(password)
    self[:password] = Digest::MD5.hexdigest(password)
  end
 
end