Active Model 实例标签助手

# File actionview/lib/action_view/helpers/active_model_helper.rb, line 20
def content_tag(type, options, *)
  select_markup_helper?(type) ? super : error_wrapping(super)
end

# File actionview/lib/action_view/helpers/active_model_helper.rb, line 36
def error_message
  object.errors[@method_name]
end

# File actionview/lib/action_view/helpers/active_model_helper.rb, line 28
def error_wrapping(html_tag)
  if object_has_errors?
    @template_object.instance_exec(html_tag, self, &Base.field_error_proc)
  else
    html_tag
  end
end

# File actionview/lib/action_view/helpers/active_model_helper.rb, line 13
def object
  @active_model_object ||= begin
    object = super
    object.respond_to?(:to_model) ? object.to_model : object
  end
end

# File actionview/lib/action_view/helpers/active_model_helper.rb, line 24
def tag(type, options, *)
  tag_generate_errors?(options) ? error_wrapping(super) : super
end