gistfile1.txt

 1) Transport::CardsController should creates card
     Failure/Error: response.code.should == '200'
       expected: "200"
            got: "500" (using ==)
     # ./spec/requests/transport/cards_spec.rb:34:in `block (2 levels) in <top (required)>'

  вот такой фильтр в transport_controller

  before_filter(:only => :create) do
    begin
      root_key = self.class.model.name.underscore.gsub('/', '_')

      unless params[root_key].blank?
        @resource = self.class.model.send(:"find_or_initialize_by_#{self.class.key}", params[root_key][self.class.key])
        @resource.assign_attributes(params[root_key])
      else
        render_error "Root attribute #{root_key} not found."
      end
    rescue ActiveRecord::UnknownAttributeError
      render_error "Missing attribute: #{$!.to_s}"
    end
  end

....

  def render_error(string)
    render :json => {:system_error => string}, :status => 500
  end