Agile Web Development with Rails, Edition 4
Agile Web Development with Rails, Edition 4
10.2 Iteration E2: Handling Errors
9.4 Playtime
10.1 Iteration E1: Creating a Smarter Cart
Change the cart to track the quantity of each product.
Add a quantity column to the line_item table in the database.
rails generate migration add_quantity_to_line_items quantity:integer
invoke active_record
create db/migrate/20111029071459_add_quantity_to_line_items.rb
Modify the migration to add a default value for the new column
edit db/migrate/20111029071459_add_quantity_to_line_items.rb
class AddQuantityToLineItems < ActiveRecord::Migration
def change
add_column :line_items, :quantity, :integer, default: 1
end
end
Apply the migration
rake db:migrate
mv 20111029071459_add_quantity_to_line_items.rb 20110711000004_add_quantity_to_line_items.rb
== AddQuantityToLineItems: migrating =========================================
-- add_column(:line_items, :quantity, :integer, {:default=>1})
-> 0.0452s
== AddQuantityToLineItems: migrated (0.0453s) ================================
Create a method to add a product to the cart by either incrementing the quantity of an existing line item, or creating a new line item.
edit app/models/cart.rb
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
Replace the call to LineItem.new with a call to the new method.
edit app/controllers/line_items_controller.rb
def create
@cart = current_cart
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,
notice: 'Line item was successfully created.' }
format.json { render json: @line_item,
status: :created, location: @line_item }
else
format.html { render action: "new" }
format.json { render json: @line_item.errors,
status: :unprocessable_entity }
end
end
end
Update the view to show both columns.
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>
Look at the cart, and see that's not exactly what we intended
get /carts/1
Pragmatic Bookshelf
Your Pragmatic Cart
- 1 × Programming Ruby 1.9
- 1 × Programming Ruby 1.9
Generate a migration to combine/separate items in carts.
rails generate migration combine_items_in_cart
invoke active_record
create db/migrate/20111029071511_combine_items_in_cart.rb
Fill in the self.up method
edit db/migrate/20111029071511_combine_items_in_cart.rb
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
Combine entries
rake db:migrate
mv 20111029071511_combine_items_in_cart.rb 20110711000005_combine_items_in_cart.rb
== CombineItemsInCart: migrating =============================================
== CombineItemsInCart: migrated (0.2704s) ====================================
Verify that the entries have been combined.
get /carts/1
Pragmatic Bookshelf
Fill in the self.down method
edit db/migrate/20110711000005_combine_items_in_cart.rb
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
Separate out individual items.
rake db:rollback
== CombineItemsInCart: reverting =============================================
== CombineItemsInCart: reverted (0.1556s) ====================================
Every item should (once again) only have a quantity of one.
get /carts/1
Pragmatic Bookshelf
Your Pragmatic Cart
- 1 × Programming Ruby 1.9
- 1 × Programming Ruby 1.9
Recombine the item data.
rake db:migrate
== CombineItemsInCart: migrating =============================================
== CombineItemsInCart: migrated (0.2622s) ====================================
Add a few products to the order.
post /line_items?product_id=2
You are being
redirected.
get http://localhost:3000/carts/1
Pragmatic Bookshelf
Line item was successfully created.
Your Pragmatic Cart
- 2 × Programming Ruby 1.9
- 1 × CoffeeScript
post /line_items?product_id=3
You are being
redirected.
get http://localhost:3000/carts/1
Pragmatic Bookshelf
Line item was successfully created.
Your Pragmatic Cart
- 3 × Programming Ruby 1.9
- 1 × CoffeeScript
Try something malicious.
get /carts/wibble
ActiveRecord::RecordNotFound
in CartsController#show
Couldn't find Cart with id=wibble
Rails.root: /home/rubys/git/awdwr/edition4/work-192/depot
Application Trace |
Framework Trace |
Full Trace
app/controllers/carts_controller.rb:16:in `show'
/home/rubys/git/rails/activerecord/lib/active_record/relation/finder_methods.rb:340:in `find_one'
/home/rubys/git/rails/activerecord/lib/active_record/relation/finder_methods.rb:311:in `find_with_ids'
/home/rubys/git/rails/activerecord/lib/active_record/relation/finder_methods.rb:107:in `find'
/home/rubys/git/rails/activerecord/lib/active_record/base.rb:444:in `find'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/implicit_render.rb:4:in `send_action'
/home/rubys/git/rails/actionpack/lib/abstract_controller/base.rb:167:in `process_action'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/rendering.rb:10:in `process_action'
/home/rubys/git/rails/actionpack/lib/abstract_controller/callbacks.rb:18:in `block in process_action'
/home/rubys/git/rails/activesupport/lib/active_support/callbacks.rb:416:in `_run__3933425017162219309__process_action__419019429871729349__callbacks'
/home/rubys/git/rails/activesupport/lib/active_support/callbacks.rb:386:in `_run_process_action_callbacks'
/home/rubys/git/rails/activesupport/lib/active_support/callbacks.rb:81:in `run_callbacks'
/home/rubys/git/rails/actionpack/lib/abstract_controller/callbacks.rb:17:in `process_action'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/rescue.rb:17:in `process_action'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
/home/rubys/git/rails/activesupport/lib/active_support/notifications.rb:53:in `block in instrument'
/home/rubys/git/rails/activesupport/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
/home/rubys/git/rails/activesupport/lib/active_support/notifications.rb:53:in `instrument'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/instrumentation.rb:29:in `process_action'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/params_wrapper.rb:198:in `process_action'
/home/rubys/git/rails/activerecord/lib/active_record/railties/controller_runtime.rb:18:in `process_action'
/home/rubys/git/rails/actionpack/lib/abstract_controller/base.rb:121:in `process'
/home/rubys/git/rails/actionpack/lib/abstract_controller/rendering.rb:45:in `process'
/home/rubys/git/rails/actionpack/lib/action_controller/metal.rb:193:in `dispatch'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
/home/rubys/git/rails/actionpack/lib/action_controller/metal.rb:236:in `block in action'
/home/rubys/git/rails/actionpack/lib/action_dispatch/routing/route_set.rb:66:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/routing/route_set.rb:66:in `dispatch'
/home/rubys/git/rails/actionpack/lib/action_dispatch/routing/route_set.rb:30:in `call'
/home/rubys/git/journey/lib/journey/router.rb:60:in `block in call'
/home/rubys/git/journey/lib/journey/router.rb:48:in `each'
/home/rubys/git/journey/lib/journey/router.rb:48:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/routing/route_set.rb:570:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
rack (1.3.5) lib/rack/etag.rb:23:in `call'
rack (1.3.5) lib/rack/conditionalget.rb:25:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/head.rb:14:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/params_parser.rb:21:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/flash.rb:247:in `call'
rack (1.3.5) lib/rack/session/abstract/id.rb:195:in `context'
rack (1.3.5) lib/rack/session/abstract/id.rb:190:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/cookies.rb:342:in `call'
/home/rubys/git/rails/activerecord/lib/active_record/query_cache.rb:64:in `call'
/home/rubys/git/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:477:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
/home/rubys/git/rails/activesupport/lib/active_support/callbacks.rb:392:in `_run_call_callbacks'
/home/rubys/git/rails/activesupport/lib/active_support/callbacks.rb:81:in `run_callbacks'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/callbacks.rb:27:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/reloader.rb:68:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/remote_ip.rb:48:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/show_exceptions.rb:48:in `call'
/home/rubys/git/rails/railties/lib/rails/rack/logger.rb:26:in `call_app'
/home/rubys/git/rails/railties/lib/rails/rack/logger.rb:16:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/request_id.rb:22:in `call'
rack (1.3.5) lib/rack/methodoverride.rb:24:in `call'
rack (1.3.5) lib/rack/runtime.rb:17:in `call'
/home/rubys/git/rails/activesupport/lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.3.5) lib/rack/lock.rb:15:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/static.rb:53:in `call'
/home/rubys/git/rails/railties/lib/rails/engine.rb:459:in `call'
rack (1.3.5) lib/rack/content_length.rb:14:in `call'
/home/rubys/git/rails/railties/lib/rails/rack/log_tailer.rb:14:in `call'
rack (1.3.5) lib/rack/handler/webrick.rb:59:in `service'
/home/rubys/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service'
/home/rubys/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run'
/home/rubys/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/server.rb:183:in `block in start_thread'
/home/rubys/git/rails/activerecord/lib/active_record/relation/finder_methods.rb:340:in `find_one'
/home/rubys/git/rails/activerecord/lib/active_record/relation/finder_methods.rb:311:in `find_with_ids'
/home/rubys/git/rails/activerecord/lib/active_record/relation/finder_methods.rb:107:in `find'
/home/rubys/git/rails/activerecord/lib/active_record/base.rb:444:in `find'
app/controllers/carts_controller.rb:16:in `show'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/implicit_render.rb:4:in `send_action'
/home/rubys/git/rails/actionpack/lib/abstract_controller/base.rb:167:in `process_action'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/rendering.rb:10:in `process_action'
/home/rubys/git/rails/actionpack/lib/abstract_controller/callbacks.rb:18:in `block in process_action'
/home/rubys/git/rails/activesupport/lib/active_support/callbacks.rb:416:in `_run__3933425017162219309__process_action__419019429871729349__callbacks'
/home/rubys/git/rails/activesupport/lib/active_support/callbacks.rb:386:in `_run_process_action_callbacks'
/home/rubys/git/rails/activesupport/lib/active_support/callbacks.rb:81:in `run_callbacks'
/home/rubys/git/rails/actionpack/lib/abstract_controller/callbacks.rb:17:in `process_action'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/rescue.rb:17:in `process_action'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
/home/rubys/git/rails/activesupport/lib/active_support/notifications.rb:53:in `block in instrument'
/home/rubys/git/rails/activesupport/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
/home/rubys/git/rails/activesupport/lib/active_support/notifications.rb:53:in `instrument'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/instrumentation.rb:29:in `process_action'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/params_wrapper.rb:198:in `process_action'
/home/rubys/git/rails/activerecord/lib/active_record/railties/controller_runtime.rb:18:in `process_action'
/home/rubys/git/rails/actionpack/lib/abstract_controller/base.rb:121:in `process'
/home/rubys/git/rails/actionpack/lib/abstract_controller/rendering.rb:45:in `process'
/home/rubys/git/rails/actionpack/lib/action_controller/metal.rb:193:in `dispatch'
/home/rubys/git/rails/actionpack/lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
/home/rubys/git/rails/actionpack/lib/action_controller/metal.rb:236:in `block in action'
/home/rubys/git/rails/actionpack/lib/action_dispatch/routing/route_set.rb:66:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/routing/route_set.rb:66:in `dispatch'
/home/rubys/git/rails/actionpack/lib/action_dispatch/routing/route_set.rb:30:in `call'
/home/rubys/git/journey/lib/journey/router.rb:60:in `block in call'
/home/rubys/git/journey/lib/journey/router.rb:48:in `each'
/home/rubys/git/journey/lib/journey/router.rb:48:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/routing/route_set.rb:570:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
rack (1.3.5) lib/rack/etag.rb:23:in `call'
rack (1.3.5) lib/rack/conditionalget.rb:25:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/head.rb:14:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/params_parser.rb:21:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/flash.rb:247:in `call'
rack (1.3.5) lib/rack/session/abstract/id.rb:195:in `context'
rack (1.3.5) lib/rack/session/abstract/id.rb:190:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/cookies.rb:342:in `call'
/home/rubys/git/rails/activerecord/lib/active_record/query_cache.rb:64:in `call'
/home/rubys/git/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:477:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
/home/rubys/git/rails/activesupport/lib/active_support/callbacks.rb:392:in `_run_call_callbacks'
/home/rubys/git/rails/activesupport/lib/active_support/callbacks.rb:81:in `run_callbacks'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/callbacks.rb:27:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/reloader.rb:68:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/remote_ip.rb:48:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/show_exceptions.rb:48:in `call'
/home/rubys/git/rails/railties/lib/rails/rack/logger.rb:26:in `call_app'
/home/rubys/git/rails/railties/lib/rails/rack/logger.rb:16:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/request_id.rb:22:in `call'
rack (1.3.5) lib/rack/methodoverride.rb:24:in `call'
rack (1.3.5) lib/rack/runtime.rb:17:in `call'
/home/rubys/git/rails/activesupport/lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.3.5) lib/rack/lock.rb:15:in `call'
/home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/static.rb:53:in `call'
/home/rubys/git/rails/railties/lib/rails/engine.rb:459:in `call'
rack (1.3.5) lib/rack/content_length.rb:14:in `call'
/home/rubys/git/rails/railties/lib/rails/rack/log_tailer.rb:14:in `call'
rack (1.3.5) lib/rack/handler/webrick.rb:59:in `service'
/home/rubys/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service'
/home/rubys/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run'
/home/rubys/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/server.rb:183:in `block in start_thread'
Request
Parameters:
{"id"=>"wibble"}
Show session dump
_csrf_token: "shxSsrJ4EsgZCfGU77/yrLqmnj0IuoeBHqTEtkctYs4="
cart_id: 1
session_id: "ce987df21f6392f8d8e8799cda3d22d8"
Show env dump
GATEWAY_INTERFACE: "CGI/1.1"
HTTP_ACCEPT: "text/html"
REMOTE_ADDR: "127.0.0.1"
REMOTE_HOST: "localhost"
SERVER_NAME: "localhost"
SERVER_PROTOCOL: "HTTP/1.1"
Response
Headers:
None
10.2 Iteration E2: Handling Errors
9.4 Playtime