RailsでTwitterBootstrapを使ったエラーメッセージ

_errors.html.erb

<% if errors.any? %>
<div class="alert alert-danger" role="alert">
  <ul>
    <% errors.full_messages.each do |message| %>
    <li><%= message %></li>
    <% end %>
  </ul>
</div>
<% end %>

_form.html.erb

<%= form_for(@user) do |f| %>

<%= render partial: 'shared/errors', object: @user.errors %>

...

<% end %>