ruby-on-rails-3 – Rails 3嵌套模型格式,2级深层使用acceptance

我的嵌套模型形式在第一层次上工作很好.但是我的印象是,你可以使用acceptance_nested_attributes_for深入许多层次.但是当我尝试下面的代码时,“ Image”属性被附加到顶层的“问题”模型,并且在使用未知属性“Image”错误的表单提交时中断.

我可以使用表单数据手工完成所有的插入,但如果Rails可以自动处理,那么明显的原因会更好.

我究竟做错了什么？我试过改变| af |在“图像做的领域”到它自己的唯一名称,但没有任何影响.

楷模：

class Question < ActiveRecord::Base
  has_one :answer
  accepts_nested_attributes_for :answer
end

class Answer < ActiveRecord::Base
  belongs_to :question
  has_one :image
  accepts_nested_attributes_for :image
end

class Image < ActiveRecord::Base
  belongs_to :answer
end

控制器：

def new
    @question = Question.new
    answer = @question.build_answer
    image = answer.build_image

    @case_id = params[:id]

    render :layout => 'application',:template => '/questions/form' 
end

def create
  question_data = params[:question]
  @question = Question.new(question_data)
  if @question.save
  ...
end

视图：

= form_for @question,:html => {:multipart => true} do |f|

  = f.label :text,"Question Text:"
  = f.text_area :text,:rows => 7

  %br
  %br

  =f.fields_for :answer,do |af|
    = af.label :body,"Answer Text:"
    = af.text_area :body,:rows => 7

    %br
    %br

    = f.fields_for :image do |af|
      = af.label :title,"Image Title:"
      = af.text_field :title

      %br

      = af.label :file,"Image File:"
      = af.file_field :file

      %br

      = af.label :caption,"Image Caption:"
      = af.text_area :caption,:rows => 7

  = hidden_field_tag("case_id",value = @case_id)

  = f.submit

= form_for @question,:rows => 7

    %br
    %br

    = af.fields_for :image do |img_form|
      = img_form.label :title,"Image Title:"
      = img_form.text_field :title

      %br

      = img_form.label :file,"Image File:"
      = img_form.file_field :file

      %br

      = img_form.label :caption,"Image Caption:"
      = img_form.text_area :caption,value = @case_id)

  = f.submit