Ruby on Rails

Hi,

I am trying to create a design for user defined tables which could be stored in a database then initialized from a controller as needed. At present I am having a bit of trouble getting these metamodels into the rails env from a controller. Is there a way that I can class_eval a model that would be able to be seen for the duration of that process?

class Admin::UdtManagersController < Admin::Auth #< ApplicationController
  before_filter :initialize_meta_environment

  def index # rails complains if this isn't here
  end

    private

      def initialize_meta_environment
        @table = 'review_processes' #define this hard coded for now... later passed via param
        @model = @table.classify

        init_models
  

      end

      def init_models
        class_eval= %q{
           class #{@model} < ActiveRecord::Base

           validates_presence_of :summary_reviews
           end
          }

       ## How can I eval this model so it will become part of my application for that process?
 
      end
end

Any help is totally appreciated! Thanks in advance.

-Mark