ruby on rails - User selects multiple items using check_box form helper; POSTs data as array -

trying convert form 1 option selected multiple items using radio_button, form multiple options can selected using check_box.

original code:

 <% @inventory.each |category, list| %>    <div class="col-xs-3">      <div class="form-group box">         <h5> <%="#{category.upcase}"%> </h5>              <% list.each |thing| %>              <%= f.radio_button(:item, "#{thing}") %>              <%= f.label(:item, "#{thing}") %>              </br>              <% end %>      </div>   </div>    <% end %> 

if nested each|dos seem confusing, what's happening there multiple categories of items being generated inventory hash. each category looks distinct on form, radio_button check on item in category counts 1 item you're selecting.

the class "request" , column data posts "item":

class request < activerecord::base     validates :item, presence: true 

i need make user can check item in category, , of items posted array. tried replacing radio_button line with:

<%= f.check_box(:item, {:multiple => true}, "#{thing}") %> 

it seems though it's working, since tested , rails debugger shows following:

request: !ruby/hash:actioncontroller::parameters   item:   - '0'   - '0'   - sleeping bag   - '0'   - sleeping pad 

however when click submit button, error message "item cannot blank."

help?

edit: add controller code:

  def new     @requestrecord = request.new     inventory #this calls private method lists items category , list     @pagetitle = "what borrow?"   end    def create     @requestrecord = request.new(request_params)     inventory     @pagetitle = "what borrow?"      if @requestrecord.save       flash[:success] = "thanks, we'll respond in few hours. below information submitted in case need change anything."       @requestrecord.save_spreadsheet       requestmailer.confirmation_email(@requestrecord).deliver       redirect_to edit_request_path(@requestrecord.edit_id)     else       render 'new'     end   end    private     def request_params       params.require(:request).permit(:email, :item, :detail, :rentdate, :edit_id)     end 

you making typical mistake when handling array type of form parameters , strong parameters.

you need tell controller it's ok accept array of "items".

so, change definition of request_params liike this:

def request_params     params.require(:request).permit(:email, {:item => []}, :detail, :rentdate, :edit_id) end 

and should on error.