Rails3 fields_for 文本哈希：未按预期工作

Question

我有一个 Rails3 表单，允许用户编辑答案列表，作为评估的一部分。
我使用 fields_for 循环生成每个文本输入：

app/models/assessment.rb :

class Assessment < ActiveRecord::Base
  serialize :answers, Hash   # answers is a t.text field used to store all answers.
end

app/view/assessments/new.html.erb :

<p>Initialized answers: <%= @assessment.answers %></p>

<% item_counter = 0 %>
<% form.fields_for :answers do |answer_fields| %>
    <% item_id = "item" + item_counter.to_s %>
    <% item_counter = item_counter + 1 %>
    <div class="field">
      <%= answer_fields.label "the appropriate question, omitted for brevity" %>
      <br/>
      <% @assessment.answers[item_id] = "" %>
      <%= answer_fields.text_field item_id, :value => @assessment.answers[item_id] %>
    </div>
<% end %>

问题： fields_for 循环进行零迭代，没有字段被打印。
（尽管“初始化答案：”正确显示：{“a”=> 143，“b”=> 42}）

Answer 1

这应该可以。本地测试过。

<p>Initialized answers: <%= @assessment.answers %></p>

<% @assessment.answers.each do |key, value| %>
  <%= form.fields_for :answers, @assessment.answers[key] do |answer_fields| %>
      <div class="field">
        <%= answer_fields.label key %>
        <br/>
        <%= answer_fields.text_field key, :value => value %>
      </div>
  <% end %>
<% end %>

Answer 2

将 Hash 转换为 OpenStruct 对象解决了我的问题。

<% form.fields_for :answers, OpenStruct.new(answers) do |answer_fields| %>
<% item_id = "item" + item_counter.to_s %>
<% item_counter = item_counter + 1 %>
<div class="field">
  <%= answer_fields.label "the appropriate question, omitted for brevity" %>
  <br/>
  <% @assessment.answers[item_id] = "" %>
  <%= answer_fields.text_field item_id, :value => @assessment.answers[item_id] %>
</div>