title: Can't get params.permit to work
body: <p>I'm posting a form with these params:</p>
  
  <pre><code>{"utf8"=&gt;"✓", "authenticity_token"=&gt;"XXXXX", "bike_part_id"=&gt;["367", "368"], 
  "commit"=&gt;"registrer en [48/1854]
   "controller"=&gt;"services", "action"=&gt;"create", "bike_id"=&gt;"10"}
  </code></pre>
  
  <p>This is the controller code:</p>
  
  <pre><code>def create
      @service = Service.new(service_params)
      @service.bike = @bike
      @service.bike_parts = @bike_parts
  
      respond_to do |format|
        if @service.save!
         #[cut..]
  end
  </code></pre>
  
  <p>-</p>
  
  <pre><code>   def service_params
        params.permit(:description, :log, :due_date, :bike_id,
                      :user_id, :completed, :bike_part_id
                      )
     end
  </code></pre>
  
  <p>But I keep getting this in the log:</p>
  
  <pre><code>Unpermitted parameters: utf8, authenticity_token, bike_part_id, commit
  </code></pre>
  
  <p>Why isn't bike_part_id allowed? </p>