_additional_field.html.erb

<!-- Note: this depends on this patch being applied:
http://github.com/simonrobson/spree/commit/5d94572bf5ba8fe8198a21dc1253845603fb3c9d -->

<p>
  <% attribute = field[:name].gsub(" ", "_").downcase %>
  <%= f.label attribute, field[:name] %>
  
  <% if f.object && f.object.column_for_attribute(attribute).type == :boolean %>
	<%= f.check_box attribute  %>
  <% else %>
  <br />
  <% val = f.object.send(attribute.to_sym) rescue nil
	formatted_value = (val.nil? || !field.key?(:format)) ? val : val % field[:format] %>
  <%= f.text_field attribute, :value => formatted_value %>
  <% end %>
  <%= f.error_message_on attribute %>
</p>