9.1 Iteration D1: Moving the Cart 8.4 Iteration C3: Handling Errors
edit app/views/store/add_to_cart.html.erb
<h2>Your Pragmatic Cart</h2>
<ul>
<% for item in @cart.items %>
<li><%= item.quantity %> × <%= item.title %></li>
<% end %>
</ul>
<%= button_to 'Empty cart', :action => 'empty_cart' %>
edit app/controllers/store_controller.rb
def empty_cart
session[:cart] = nil
flash[:notice] = "Your cart is currently empty"
redirect_to :action => 'index'
end
get /store/empty_cart
get http://localhost:3000/store/index
Pragmatic Bookshelf
Pragmatic Project Automation shows you how to improve the consistency and repeatability of your project's procedures using automation to reduce risk and errors.
Simply put, we're going to put this thing called a computer to work for you doing the mundane (but important) project stuff. That means you'll have more time and energy to do the really exciting---and difficult---stuff, like writing quality code.
Pragmatic programmers use feedback to drive their development and personal processes. The most valuable feedback you can get while coding comes from unit testing.
Without good tests in place, coding can become a frustrating game of "whack-a-mole." That's the carnival game where the player strikes at a mechanical mole; it retreats and another mole pops up on the opposite side of the field. The moles pop up and down so fast that you end up flailing your mallet helplessly as the moles continue to pop up where you least expect them.
This book is a recipe-based approach to using Subversion that will get you up and running quickly---and correctly. All projects need version control: it's a foundational piece of any project's infrastructure. Yet half of all project teams in the U.S. don't use any version control at all. Many others don't use it well, and end up experiencing time-consuming problems.
edit app/controllers/store_controller.rb
def add_to_cart
product = Product.find(params[:id])
@cart = find_cart
@cart.add_product(product)
rescue ActiveRecord::RecordNotFound
logger.error("Attempt to access invalid product #{params[:id]}")
redirect_to_index("Invalid product")
end
def empty_cart
session[:cart] = nil
redirect_to_index("Your cart is currently empty")
end
private
def redirect_to_index(msg)
flash[:notice] = msg
redirect_to :action => 'index'
end
edit app/views/store/add_to_cart.html.erb
<div class="cart-title">Your Cart</div>
<table>
<% for item in @cart.items %>
<tr>
<td><%= item.quantity %>×</td>
<td><%=h item.title %></td>
<td class="item-price"><%= number_to_currency(item.price) %></td>
</tr>
<% end %>
<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", :action => :empty_cart %>
edit public/stylesheets/depot.css
/* Styles for the cart in the main page */
.cart-title {
font: 120% bold;
}
.item-price, .total-line {
text-align: right;
}
.total-line .total-cell {
font-weight: bold;
border-top: 1px solid #595;
}
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
@items << CartItem.new(product)
end
end
def total_price
@items.sum { |item| item.price }
end
end
get /store/add_to_cart/2
Pragmatic Bookshelf
get /store/add_to_cart/2
Pragmatic Bookshelf
get /store/add_to_cart/3
Pragmatic Bookshelf
9.1 Iteration D1: Moving the Cart 8.4 Iteration C3: Handling Errors