10.4 Playtime 10.2 Iteration E2: Handling Errors
Add empty cart button, remove flash for line item create, add totals to view.
Add button to the view.
edit app/views/carts/show.html.erb
<% if notice %>
<p id="notice"><%= notice %></p>
<% end %>
<h2>Your Pragmatic Cart</h2>
<ul>
<% @cart.line_items.each do |item| %>
<li><%= item.quantity %> × <%= item.product.title %></li>
<% end %>
</ul>
<%= button_to 'Empty cart', @cart, method: :delete,
data: { confirm: 'Are you sure?' } %>
Clear session and change flash notice when cart is destroyed.
edit app/controllers/carts_controller.rb
def destroy
@cart.destroy if @cart.id == session[:cart_id]
session[:cart_id] = nil
respond_to do |format|
format.html { redirect_to store_url,
notice: 'Your cart is currently empty' }
format.json { head :no_content }
end
end
Try it out.
get /carts/1
Pragmatic Bookshelf
post /carts/1
get http://localhost:3000/
Pragmatic Bookshelf
Your cart is currently empty
CoffeeScript is JavaScript done right. It provides all of JavaScript's functionality wrapped in a cleaner, more succinct syntax. In the first book on this exciting new language, CoffeeScript guru Trevor Burnham shows you how to hold onto all the power and flexibility of JavaScript while writing clearer, cleaner, and safer code.
Ruby is the fastest growing and most exciting dynamic language out there. If you need to get working programs delivered fast, you should add Ruby to your toolbox.
Rails Test Prescriptions is a comprehensive guide to testing Rails applications, covering Test-Driven Development from both a theoretical perspective (why to test) and from a practical perspective (how to test effectively). It covers the core Rails testing tools and procedures for Rails 2 and Rails 3, and introduces popular add-ons, including Cucumber, Shoulda, Machinist, Mocha, and Rcov.
Remove scaffolding generated flash notice for line item create.
edit app/controllers/line_items_controller.rb
def create
product = Product.find(params[:product_id])
@line_item = @cart.add_product(product.id)
respond_to do |format|
if @line_item.save
format.html { redirect_to @line_item.cart }
format.json { render :show,
status: :created, location: @line_item }
else
format.html { render :new }
format.json { render json: @line_item.errors,
status: :unprocessable_entity }
end
end
end
Update the view to add totals.
edit app/views/carts/show.html.erb
<% if notice %>
<p id="notice"><%= notice %></p>
<% end %>
<h2>Your Cart</h2>
<table>
<% @cart.line_items.each do |item| %>
<tr>
<td><%= item.quantity %>×</td>
<td><%= item.product.title %></td>
<td class="item_price"><%= number_to_currency(item.total_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', @cart, method: :delete,
data: { confirm: 'Are you sure?' } %>
Add a method to compute the total price of a single line item.
edit app/models/line_item.rb
def total_price
product.price * quantity
end
Add a method to compute the total price of the items in the cart.
edit app/models/cart.rb
def total_price
line_items.to_a.sum { |item| item.total_price }
end
Add some style.
edit app/assets/stylesheets/carts.css.scss
.carts {
.item_price, .total_line {
text-align: right;
}
.total_line .total_cell {
font-weight: bold;
border-top: 1px solid #595;
}
}
Add a product to the cart, and see the total.
get /
Pragmatic Bookshelf
CoffeeScript is JavaScript done right. It provides all of JavaScript's functionality wrapped in a cleaner, more succinct syntax. In the first book on this exciting new language, CoffeeScript guru Trevor Burnham shows you how to hold onto all the power and flexibility of JavaScript while writing clearer, cleaner, and safer code.
Ruby is the fastest growing and most exciting dynamic language out there. If you need to get working programs delivered fast, you should add Ruby to your toolbox.
Rails Test Prescriptions is a comprehensive guide to testing Rails applications, covering Test-Driven Development from both a theoretical perspective (why to test) and from a practical perspective (how to test effectively). It covers the core Rails testing tools and procedures for Rails 2 and Rails 3, and introduces popular add-ons, including Cucumber, Shoulda, Machinist, Mocha, and Rcov.
post /line_items?product_id=2
get http://localhost:3000/carts/2
Add a few more products, and watch the totals climb!
post /line_items?product_id=2
get http://localhost:3000/carts/2
post /line_items?product_id=3
get http://localhost:3000/carts/2
Pragmatic Bookshelf