Smarter Cart--with total amount displayed

app/assets/stylesheets/carts.css.scss

@@ -1,3 +1,15 @@
 // 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/
+
+.carts {
+  .item_price, .total_line {
+    text-align: right;
+  }
+
+  .total_line .total_cell {
+    font-weight: bold;
+    border-top: 1px solid #595;
+  }
+}
+

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
 
@@ -72,12 +77,15 @@ 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
 end
+

app/controllers/line_items_controller.rb

@@ -42,14 +42,11 @@ def edit
   def create
     @cart = current_cart
     product = Product.find(params[:product_id])
-    #@line_item = @cart.line_items.build(product_id: product)
     @line_item = @cart.add_product(product.id)
-    #@line_item = @cart.add_product(product_id: product.id)
 
     respond_to do |format|
       if @line_item.save
-        format.html { redirect_to @line_item.cart,
-          notice: 'Line item was successfully created.' }
+        format.html { redirect_to @line_item.cart }
         format.json { render json: @line_item,
           status: :created, location: @line_item }
       else

app/models/cart.rb

@@ -12,5 +12,9 @@ def add_product(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

@@ -5,5 +5,9 @@ class LineItem < ActiveRecord::Base
 
   belongs_to :product
   belongs_to :cart
+
+  def total_price
+    product.price * quantity
+  end
 end
 

app/views/carts/show.html.erb

@@ -2,10 +2,21 @@
 <p id="notice"><%= notice %></p>
 <% end %>
 
-<h2>Your Pragmatic Cart</h2>
-<ul>
+<h2>Your Cart</h2>
+<table>
   <% @cart.line_items.each do |item| %>
-    <li><%= item.quantity %> &times; <%= 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,
+    data: { confirm: 'Are you sure?' } %>
 

test/functional/carts_controller_test.rb

@@ -41,9 +41,11 @@ 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
+