Task E

app/assets/stylesheets/carts.css.scss

@@ -1,3 +1,19 @@
 // Place all the styles related to the carts controller here.
 // They will automatically be included in application.css.
 // You can use Sass (SCSS) here: http://sass-lang.com/
+/* START_HIGHLIGHT */
+.carts {
+  .cart_title {
+    font: 120% bold;
+  }
+
+  .item_price, .total_line {
+    text-align: right;
+  }
+
+  .total_line .total_cell {
+    font-weight: bold;
+    border-top: 1px solid #595;
+  }
+}
+/* END_HIGHLIGHT */

app/controllers/carts_controller.rb

@@ -13,11 +13,16 @@ def index
   # GET /carts/1
   # GET /carts/1.json
   def show
-    @cart = Cart.find(params[:id])
-
-    respond_to do |format|
-      format.html # show.html.erb
-      format.json { render json: @cart }
+    begin
+      @cart = Cart.find(params[:id])
+    rescue ActiveRecord::RecordNotFound
+      logger.error "Attempt to access invalid cart #{params[:id]}"
+      redirect_to store_url, notice: 'Invalid cart'
+    else
+      respond_to do |format|
+        format.html # show.html.erb
+        format.json { render json: @cart }
+      end
     end
   end
 
@@ -72,11 +77,13 @@ def update
   # DELETE /carts/1
   # DELETE /carts/1.json
   def destroy
-    @cart = Cart.find(params[:id])
+    @cart = current_cart
     @cart.destroy
+    session[:cart_id] = nil
 
     respond_to do |format|
-      format.html { redirect_to carts_url }
+      format.html { redirect_to store_url,
+                                notice: 'Your cart is currently empty' }
       format.json { head :no_content }
     end
   end

app/controllers/line_items_controller.rb

@@ -42,12 +42,12 @@ def edit
   def create
     @cart = current_cart
     product = Product.find(params[:product_id])
-    @line_item = @cart.line_items.build(product: product)
+    @line_item = @cart.add_product(product.id)
 
     respond_to do |format|
       if @line_item.save
-        session[:counter] = nill
-        format.html { redirect_to @line_item.cart, notice: 'Line item was successfully created.' }
+        session[:counter] = nil
+        format.html { redirect_to @line_item.cart }
         format.json { render json: @line_item, status: :created, location: @line_item }
       else
         format.html { render action: "new" }

app/models/cart.rb

@@ -1,3 +1,17 @@
 class Cart < ActiveRecord::Base
   has_many :line_items, dependent: :destroy
-end
+
+  def add_product(product_id)
+    current_item = line_items.find_by_product_id(product_id)
+    if current_item
+      current_item.quantity += 1
+    else
+      current_item = line_items.build(product_id: product_id)
+    end
+    current_item
+  end
+  def total_price
+    line_items.to_a.sum { |item| item.total_price }
+  end
+
+end

app/models/line_item.rb

@@ -1,4 +1,9 @@
 class LineItem < ActiveRecord::Base
   belongs_to :product
   belongs_to :cart
+
+  def total_price
+    product.price * quantity
+  end
+
 end

app/views/carts/show.html.erb

@@ -1,9 +1,20 @@
 <% if notice %>
     <p id="notice"><%= notice %></p>
 <% end %>
-<h2>Your Pragmatic Cart</h2>
-<ul>
+<div class="cart_title">Your Cart</div>
+<table>
   <% @cart.line_items.each do |item| %>
-      <li><%= item.product.title %></li>
+      <tr>
+        <td><%= item.quantity %>&times;</td>
+        <td><%= item.product.title %></td>
+        <td class="item_price"><%= number_to_currency(item.total_price) %></td>
+      </tr>
   <% end %>
-</ul>
+  <tr class="total_line">
+    <td colspan="2">Total</td>
+    <td class="total_cell"><%= number_to_currency(@cart.total_price) %></td>
+  </tr>
+</table>
+<%= button_to 'Empty cart', @cart, method: :delete,
+              confirm: 'Are you sure?' %>
+

db/migrate/20120328130343_add_quantity_to_line_items.rb

@@ -0,0 +1,5 @@
+class AddQuantityToLineItems < ActiveRecord::Migration
+  def change
+    add_column :line_items, :quantity, :integer, default: 1
+  end
+end

db/migrate/20120328135252_combine_items_in_cart.rb

@@ -0,0 +1,30 @@
+class CombineItemsInCart < ActiveRecord::Migration
+  def up
+# replace multiple items for a single product in a cart with a single item
+    Cart.all.each do |cart|
+# count the number of each product in the cart
+      sums = cart.line_items.group(:product_id).sum(:quantity)
+      sums.each do |product_id, quantity|
+        if quantity > 1
+# remove individual items
+          cart.line_items.where(product_id: product_id).delete_all
+# replace with a single item
+          cart.line_items.create(product_id: product_id, quantity: quantity)
+        end
+      end
+    end
+  end
+
+  def down
+# split items with quantity>1 into multiple items
+    LineItem.where("quantity>1").each do |line_item|
+# add individual items
+      line_item.quantity.times do
+        LineItem.create cart_id: line_item.cart_id,
+                        product_id: line_item.product_id, quantity: 1
+      end
+# remove original item
+      line_item.destroy
+    end
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20120326193046) do
+ActiveRecord::Schema.define(:version => 20120328135252) do
 
   create_table "carts", :force => true do |t|
     t.datetime "created_at", :null => false
@@ -21,8 +21,9 @@
   create_table "line_items", :force => true do |t|
     t.integer  "product_id"
     t.integer  "cart_id"
-    t.datetime "created_at", :null => false
-    t.datetime "updated_at", :null => false
+    t.datetime "created_at",                :null => false
+    t.datetime "updated_at",                :null => false
+    t.integer  "quantity",   :default => 1
   end
 
   create_table "products", :force => true do |t|

test/functional/carts_controller_test.rb

@@ -41,9 +41,10 @@ class CartsControllerTest < ActionController::TestCase
 
   test "should destroy cart" do
     assert_difference('Cart.count', -1) do
+      session[:cart_id] = @cart.id
       delete :destroy, id: @cart
     end
 
-    assert_redirected_to carts_path
+    assert_redirected_to store_path
   end
 end