_hidden_order.html.erb

<% @shop_order.attributes.each do |column| %>
<% next if column[0] == 'how_did_you_hear' %>
  <input type=hidden name="shop_order[<%=h column[0] %>]" value="<%=h column[1] %>" />
<% end %>
<%# attr_accessors aren't in the attributes array %>
<% @shop_order.accessors.each do |a| %>
  <input type=hidden name="shop_order[<%= a %>]" value="<%=h eval("@shop_order."+a) %>" />
<% end %>

shop_order.rb

class ShopOrder < ActiveRecord::Base
  # list of accessors we need to keep in the track
  def accessors
    ['creditcard_type','creditcard_number','creditcard_exp_month','creditcard_exp_year','creditcard_ccv']
  end

  # Fields we don't record in the database
  attr_accessor :creditcard_type
  attr_accessor :creditcard_number
  attr_accessor :creditcard_exp_month
  attr_accessor :creditcard_exp_year
  attr_accessor :creditcard_ccv
end