class User < Sequel::Model
  validates do
    presence_of :email_address
    presence_of :password_salt
    presence_of :password_hash
  end

  def password_mismatch
    @password_mismatch ||= false
  end
  def password_mismatch=(val)
    @password_mismatch = val
  end

  validates_each :password_mismatch do |object,attribute,value|
    raise @password_mismatch.inspect
    if @password_mismatch
      object.errors[attribute] << "does not match"
    end
  end

  before_create do
    self.signed_up_on = Time.now
  end

  def password=(pass)
    @password = pass
    # This is for generating the keys
    salt = [Array.new(6){rand(256).chr}.join].pack("m").chomp
    self.password_salt, self.password_hash = salt, Digest::SHA256.hexdigest(pass+salt)
  end

  def self.authenticate(email_address, password)
    user = User.where{:email_address == email_address}.first
    if user.nil? || Digest::SHA256.hexdigest(password + user.password_salt) != user.password_hash
      raise "Username or password invalid"
    end
    user
  end
end


>> u = User.new(:email_address => "hey@hey.com", :password_mismatch => true); u.valid?
RuntimeError: nil