Rails: radio button selection for nested objects -

i'm stuck simple selection task. have models:

#  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 

when create new question, want specify in nested form not content of question, content of 3 answer objects, , select radio button 1 correct answer. in new action of controller, have this:

def new     @title = "new question"     @question = question.new     3.times { @question.choices.build }      respond_to |format|         format.html # new.html.erb         format.xml  { render :xml => @question }     end end 

this form code:

<%= simple_form_for @question |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 |choice| %>         <%= question_form.fields_for :choices, choice |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 %> 

the problem code produce 3 radio buttons different names: can select more 1 correct answer, , not correct behaviour. names of 3 radio buttons question[choices_attributes][0][correct], question[choices_attributes][1][correct] , question[choices_attributes][2][correct].

the question is: how can create 3 radio buttons same name, in order select 1 , 1 correct answer? how can create correct params array, in order save them in create action in way:

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

thank much!

you can use radio_button_tag , pass own name attribute.

being still in choice_fields scope, have access few methods can expose object working on, name radio_button_tag properly.

the following code give radio button proper name accepted nested attribute:

<%= radio_button_tag "question[choices_attributes][#{choice_fields.index}][correct]", true, choice_fields.object.correct %>

choice_fields.index gives access proper index of resource being created, first coice have name question[choices_attributes][0][correct], second 1 question[choices_attributes][1][correct], etc.

choice_fields.object.correct gives access current value correct radio button filled in edit forms.

update: solution above wrong, gives each radio button different name attribute don't end working (you can select multiple radio buttons @ once).

the soltion ended going allong following lines:

<%= radio_button_tag "question[choices_attributes][correct_choice]", choice_fields.index, choice_fields.object.correct %> 

this gives each radio button same name others, , value equal index of correct choice. params hash ends looking this:

question: {choices_attributes: {         "0": {//choice 0},         "1": {//choice 1},         etc...     },     correct_choice: //index of correct answer } 

i updated controller manually update correct choice follows:

def create     correct_index = params[:question][:correct_choice]     params[:question][:choiceses_attributes][correct_index][:correct] = true     @question = question.new(params[:question])     # render or redirect stuff.... end