start_form_tag 方法没定义

start_form_tag 和end_form_tag方法已经被废弃了，现在是 <% form_tag  ...  do%><% end -%>

参看例子：（《Agile Web Development with Rails》中p105 checkout.rhtml ）

<% @page_title = "Checkout" -%>
 <% form_tag (:action => "save_order") do %>
<table>
 <tr>
    <td>Name :</td>
    <td><%= text_field ("Order", "name", "size" => 40) %></td>
    </tr>
    <tr>
    <td>Email: </td>
    <td><%= text_field("order", "email", "size" =>40) %> </td>
    </tr>
    <tr valign="top">
    <td>Address:</td>
    <td><%= text_area("order","address", "cols"=>40, "rows"=>5) %> </td>
    </tr>
    <tr>
    <td> Pay using: </td>
    <td><%=
    options =[["Select a payment option",""]]+Order::PAYMENT_TYPES
    select("order","pay_type",options)
    %></td>
    </tr>
    <tr>
    <td></td>
    <td> <%= submit_tag(" CHECKOUT ")%></td>
    </tr>
    </table>
    <% end -%>