The Depot Application

9.4 Iteration D4: Hide an Empty Cart

edit app/views/store/add_to_cart.js.rjs

page.replace_html("cart", :partial => "cart", :object => @cart)

page[:cart].visual_effect :blind_down if @cart.total_items == 1

page[:current_item].visual_effect :highlight,

                                  :startcolor => "#88ff88",

                                  :endcolor => "#114411"

edit app/models/cart.rb

class Cart

  attr_reader :items   # <wtf linkend="wtf.attr.accessor">attr_reader</wtf>

  def initialize

    @items = []

end

  def add_product(product)

    current_item = @items.find {|item| item.product == product}

    if current_item

      current_item.increment_quantity

    else

      current_item = CartItem.new(product)

      @items << current_item

end

    current_item

end

  def total_price

    @items.sum { |item| item.price }

end

  def total_items

    @items.sum { |item| item.quantity }

end

end

ls -p app

controllers/

helpers/

mailers/

models/

views/

ls -p app/helpers

application_helper.rb

products_helper.rb

store_helper.rb

edit app/views/layouts/store.html.erb

      <%= hidden_div_if(@cart.items.empty?, :id => 'cart') do %>

        <%= render(:partial => "cart", :object => @cart) %>

      <% end %>

edit app/helpers/store_helper.rb

module StoreHelper

  def hidden_div_if(condition, attributes = {}, &block)

    if condition

      attributes["style"] = "display: none"

end

    content_tag("div", attributes, &block)

end

end

edit app/controllers/store_controller.rb

  def empty_cart

    session[:cart] = nil

    redirect_to_index

end