ROR radio buttons for dummies?

Question

I have read the documentation on this, and still i have no idea how to do this.

I have a column in the table for :free that is a boolean

true  = free
false = paid
nil   = both

I'm trying to capture this same logic in my form and i'm doing an absolutely terrible job... so far everything comes up as free

index.html.erb:

 <div class="field">
    <label class="radio">
      <%= radio_button_tag(:free, "free", :checked => true) %>
      Free
    </label>
    <label class="radio">
      <%= radio_button_tag(:free, "paid") %>
      Paid
    </label>
    <label class="radio">
      <%= radio_button_tag(:free, "both") %>
      Both
    </label>
  </div>

resources_controller.rb (I know this isnt ideal because its checking the params every single time (even if they enter in wrong info) but i'm not sure how else to check if i can save it without saving it. Also... I dont even know if i did params right but i am not sure how to check it either. when i do p params[:resources] it doesnt print it how id like it to. is there a good way to do this kind of thing in rails?

def create
    @resource = Resource.new(params[:resource])

    if params[:resource][:free] = "free"
      @resource[:free] = true
    elsif params[:resource][:free] = "both"
      @resource[:free] = nil
    else
      @resource[:free] = false
    end

    if @resource.save
      redirect_to root_url
    else
      render :action => :new
    end 
  end

resources_helper.rb

  def output_free
    if @resource.free = true
      "Free"
    elsif @resource.free = false
      "Paid"
    else
      "Both"
    end
  end

Answer 1

That's fuzzy logic, true/false/null. Does exist in SQL, you could used that, but that's magic you don't want. Use an Enum and three states - way clearer.

And use == to compare :-)