rails3下,<%= f.error_messages %>替换为
<%if@post.errors.any?%>
<div id="error_explanation">
<h2><%= pluralize(@post.errors.count,"error")%> prohibited this post from being saved:</h2>
<ul>
<%@post.errors.full_messages.each do|msg|%>
<li><%= msg %></li>
<%end%>
</ul>
</div>
<%end%>