## Error:

undefined method `blank' for "03290aa3b91050b34eba644409c2769e828b15e5":String

#{RAILS_ROOT}/app/models/user.rb:9:in `validate'
#{RAILS_ROOT}/app/controllers/login_controller.rb:4:in `add_user'

----- user.rb --------
class User < ActiveRecord::Base
  validates_presence_of :name
  validates_uniqueness_of :name

  attr_accessor :password_confirmation
  validates_confirmation_of :password

  def validate
    errors.add_to_base("Missing password") if hashed_password.blank;
  end

  def password
    @password
  end

  def password=(pwd)
    @password = pwd
    create_new_salt
    self.hashed_password = User.encrypted_password(self.password, self.salt)
  end

  def self.authenticate(name, password)
    user = self.find_by_name(name)
    if user
      expected_password = encrypted_password(password, user.salt)
      if user.hashed_password != expected_password
        user = nil
      end
    end
    user
  end

  private
  def self.encrypted_password(password, salt)
    string_to_hash = password   "tribble"   salt # 'tribble' makes it harder to guess
    Digest::SHA1.hexdigest(string_to_hash)
  end

  def create_new_salt
    self.salt = self.object_id.to_s   rand.to_s
  end
end

------------- add_user function -------------
  def add_user
    @user = User.new(params[:user])
(4)   if request.post? and @user.save
      flash.now[:notice] = "User #{@user.name} created"
      @user = User.new
    end
  end