module DataMapper::ActiveModel::InstanceMethods

def errors
  obj = Object.new
  def obj.[](key)         [] end
  def obj.full_messages() [] end
  obj
end

def persisted?
  saved?
end

def to_key
  key
end

def to_model
  self
end

def to_param
  return nil if key.nil?
  if key.length > 1
    raise "You need to implement #to_param yourself to support this key: #{self.class.key.inspect}"
  else
    self.key.first.to_s
  end
end

def valid?
  true
end