update_multiple.rb

  def update_multiple
    @items = Item.find(params[:item_ids])
    @items.each do |item|
      item.attributes = params[:item].reject { |k,v| v.blank? }
    end
    if @items.all?(&:valid?)
      @items.each(&:save!)
      flash[:notice] = "Updated items!"
      redirect_to items_path
    else
      flash[:notice] = "Please enter valid data."
      render :action => 'edit_multiple'
    end
  end