rails的表单验证后格式错乱问题

Question

举个例子，在表单中有这样的内容：

    <dl>                                                                                                                                                                                                                                                                        
      <dt>
        <%= f.label :subject %>
      </dt>
      <dd>
        <%= f.text_field :subject %>
      </dd>
    </dl>

在浏览器中显示成：

■Subject

(※注：■由CSS生成)

如果对表单进行验证，验证后再显示的格式就乱了，变成这样：

■
Subject

为什么会错位呢？

Answer 1

You should override ActionView::Base.field_error_proc. It's currently defined as this within ActionView::Base:

 @@field_error_proc = Proc.new{ |html_tag, instance| 
   "<div class=\"field_with_errors\">#{html_tag}</div>".html_safe
 }

You can override it by putting this in your application's class inside config/application.rb:

config.action_view.field_error_proc = Proc.new { |html_tag, instance| 
  "#{html_tag}".html_safe 
}

Restart rails server for this change to take effect.

（全文抄袭自 http://stackoverflow.com/questions/5267998/rails-3-field-with-errors-wrapper-changes-the-page-appearance-how-to-avoid-t）

---

当然，更推荐改成这样

config.action_view.field_error_proc = Proc.new do |html_tag, instance|
  class_attr_index = html_tag.index 'class='

  if class_attr_index
    html_tag.insert class_attr_index+7, 'error '
  else
    html_tag.insert html_tag.index('>'), ' class="error"'
  end
end