#  id         :integer(4)      not null,primary key
#  category   :string(255)
#  content    :text
class Question < ActiveRecord::Base
    has_many :choices,:dependent => :destroy
    accepts_nested_attributes_for :choices
end

#  id          :integer(4)      not null,primary key
#  content     :text
#  correct     :boolean(1)
#  question_id :integer(4) 
class Choice < ActiveRecord::Base
    belongs_to :question
end

当我创建一个新问题时,我想以嵌套形式指定问题的内容,甚至指定3个答案对象的内容,并选择一个单选按钮,哪一个是正确的答案.在控制器的新动作中,我有：

def new
    @title = "New Question"
    @question = Question.new
    3.times { @question.choices.build }

    respond_to do |format|
        format.html # new.html.erb
        format.xml  { render :xml => @question }
    end
end

这是表单代码：

<%= simple_form_for @question do |question_form| %>
    <%= question_form.error_notification %>

    <div class="inputs">
    <%= question_form.input :content,:label => 'Question' %>
    <%= question_form.input :category,:collection => get_categories,:include_blank => false %>

    <% @question.choices.each do |choice| %>
        <%= question_form.fields_for :choices,choice do |choice_fields| %>
            <%= choice_fields.input :content,:label => 'Choice' %>
            <%= choice_fields.radio_button :correct,true %>
            <%= choice_fields.label :correct,'Correct Answer' %>
        <% end %>
    <% end %>
    </div>

    <div class="actions">
    <%= question_form.button :submit %>
    </div>
<% end %>

问题是这个代码产生三个不同名称的单选按钮：你可以选择多个正确的答案,这不是正确的行为.三个单选按钮的名称是问题[choice_attributes] [0] [正确],问题[choice_attributes] [1] [正确]和问题[choice_attributes] [2] [正确].

问题是：如何创建三个具有相同名称的单选按钮,以便选择一个唯一的正确答案？如何创建一个正确的params数组,以便以这种方式将它们保存在创建操作中：

def create
    @question = Question.new(params[:question])
    # render or redirect stuff....
end

非常感谢你！