Errors with no DB

Hi,

I'm just starting with RubyMine, I'm also new to Ruby and RoR.

I'm building a web site without a database as it's going to consume services rather than a database backend directly.  I've initially configured the new application as per this post of SO http://stackoverflow.com/questions/3954307/rails-3-how-do-i-avoid-database-altogether

I've created a model for my application as per this method using ActiveModel http://railscasts.com/episodes/219-active-model however when I run a code inspection on the class:

class PlotBase
  include ActiveModel::Validations
  include ActiveModel::Conversion
  extend ActiveModel::Naming

  attr_accessor :id, :xCoor, :xCoor, :notes

  validates_presence_of :id
  validates_presence_of :xCoor
  validates_presence_of :yCoor

  def initialize(attributes = {})
    attributes.each do |name, value|
      send("#{name}=", value)
    end
  end

  def persisted?
    false
  end

end

RubyMine is reporting a number of errors on the class but it's falls in line with the structure contained in the RailCast demo (and as per the full source for the same demo).  The errors include:

• Cannot find variable with given name

Unless I also include:

  def self.id
    # code here
  end

It also reports:

• DB field ':id' of undefined table for class 'PlotBase' or unable to find Rails Model association with name ':id'

Which I was assuming that the persisted method denotes this isn't a model linked to a corresponding database table.

I must be missing something obvious as I'm a complete noob so any pointers on the class structure would also be appreciated.

Thanks,

James