我有一个包含一堆字段的相当基本的表单。这是一段摘录：
<%= form_for(@subject) do |f| %>
<% if @subject.errors.any? %>
<div id="error_explanation">
<h2><%= t('activerecord.errors.subject.header', :model => Subject.model_name.human, :count => @subject.errors.count) %></h2>
<ul>
<% @subject.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="group">
<fieldset class="left">
<div class="field">
<%= f.label "Anrede" %>
<%= f.radio_button :title, "Herr" %>
<%= f.label :title_herr, "Herr", class: "radio" %>
<%= f.radio_button :title, "Frau" %>
<%= f.label :title_frau, "Frau", class: "radio" %>
</div>
<div class="field">
<%= f.label :name %>
<%= f.text_field :firstname, class: "m", placeholder: "Vorname" %>
<%= f.text_field :lastname, class: "m", placeholder: "Nachname" %>
</div>
<div class="field">
<%= f.label "Stadt" %>
<%= f.select :city, Subject::CITIES, prompt: "- Bitte wählen -" %>
</div>
控制器主要还是来自脚手架：
# POST /subjects
# POST /subjects.json
def create
@subject = Subject.new(subject_params)
respond_to do |format|
if @subject.save
format.html { }
format.json { render action: 'create', status: :created, location: @subject }
else
format.html { render action: 'new' }
format.json { render json: @subject.errors, status: :unprocessable_entity }
end
end
end
但是，当提交无效的表单时，它会显示#error_explanation-div，但不会div.field_with_error像以前那样包装错误的字段。真的不知道是什么改变让它崩溃了。