User selects multiple items using check_box form helper; POSTs data as array

Question

Trying to convert a form where previously only one option could be selected from multiple items using radio_button, to a form where multiple options can be selected using check_box.

Original code:

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

If all the nested each|dos seem confusing, basically what's happening is there are multiple categories of items being generated from an inventory hash. Each category looks distinct on the form, but a radio_button check on any item in any category counts as the one item you're selecting.

The class is "Request" and the column that this data posts to is "Item":

class Request < ActiveRecord::Base
    validates :item, presence: true

I need to now make it so that a user can check any item in any category, and all of those items are POSTed as an array. I tried replacing the radio_button line with:

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

It seems as though it's working, since I just tested and the Rails debugger shows the following:

request: !ruby/hash:ActionController::Parameters
  item:
  - '0'
  - '0'
  - Sleeping bag
  - '0'
  - Sleeping pad

However when I click the submit button, I get the error message that "Item cannot be blank."

Help?

EDIT: add controller code:

  def new
    @requestrecord = Request.new
    inventory #This calls a private method that lists all the items by category and list
    @pagetitle = "What would you like to borrow?"
  end

  def create
    @requestrecord = Request.new(request_params)
    inventory
    @pagetitle = "What would you like to borrow?"

    if @requestrecord.save
      flash[:success] = "Thanks, we'll respond in a few hours. Below is the information you submitted in case you need to 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

Answer 1

You are making a typical mistake when handling array type of form parameters and strong parameters.

You need to tell the controller that it's ok to accept an array of "items".

So, change your definition of request_params liike this:

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

And it should be over with this error.