call_flow.rb

class CallFlow < ActiveRecord::Base
  establish_connection "callengine_#{Rails.env}"
  belongs_to :routable, :polymorphic => true

  def dialplan
    puts self.routable.description.squeeze("\n").strip
  end

  def target_route=(params)
    self.routable = params[:kind].constantize.new(params.reject {|k,v| k == "kind"})
  end
end

services_controller.rb

    case params[:route_type]
      when "simple"
        # Setup the nested attributes to pass to the models and create a callflow 
        # validate_hash is a flat hash of attributes meant for the CallFlow model
        @nested_attributes = validate_hash[:criteria].merge({
          'target_route' => {
            'kind' => 'RouteByMessage',
            'message_options_attributes' => {
              'message' => message,
              'target_did' => ringto
            }
          }
        })
        call_flow = CallFlow.create(@nested_attributes)