Rails: バリデーションエラーをViewに表示する

Remember our .errors.full_messages from using ActiveRecord before? We'll just go through each error message and display it as part of a bulleted list:

<%= form_for @movie do |f| %>
  <% if @movie.errors.any? %>
    <div>
      <%= pluralize(@movie.errors.count, "error") %> prevented this movie from being submitted:
      <ul>
        <% @movie.errors.full_messages.each do |msg| %>
          <li><%= msg %></li>
        <% end %>
      </ul>
    </div>
  <% end %>
  [...]
<% end %>