Rails2.0 Droppable&Sortable need url

Rails2.0 require pseudo url with drop_receiving_element and sortable_element helper, like as

<%= sortable_element :drop, :url => {:action => 'hello'} %>

sortable_element : You have a nil object when you didn't expect it! - PeepCode | Google グループ

但し、onUpdateはリストにunderscore+serial numberを付けてこうやる

＜ul id="list">
＜li id='item_1'>Buy milk
＜li id='item_2'>Take out trash
＜li id='item_3'>Make first million
＜/ul>

＜%= sortable_element :list, :onUpdate => "function(el){alert(el.innerHTML)}" %>