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/20140923074107_add_quantity_to_line_items.rb
Modify the migration to add a default value for the new column
edit db/migrate/20140923074107_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 20140923074107_add_quantity_to_line_items.rb 20140923000004_add_quantity_to_line_items.rb
== 20140923000004 AddQuantityToLineItems: migrating ===========================
-- add_column(:line_items, :quantity, :integer, {:default=>1})
-> 0.0030s
== 20140923000004 AddQuantityToLineItems: migrated (0.0031s) ==================
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
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 :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 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 & 2.0
- 1 × Programming Ruby 1.9 & 2.0
Generate a migration to combine/separate items in carts.
rails generate migration combine_items_in_cart
invoke active_record
create db/migrate/20140923074110_combine_items_in_cart.rb
Fill in the self.up method
edit db/migrate/20140923074110_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
item = cart.line_items.build(product_id: product_id)
item.quantity = quantity
item.save!
end
end
end
end
Combine entries
rake db:migrate
mv 20140923074110_combine_items_in_cart.rb 20140923000005_combine_items_in_cart.rb
== 20140923000005 CombineItemsInCart: migrating ===============================
== 20140923000005 CombineItemsInCart: migrated (0.0221s) ======================
Verify that the entries have been combined.
get /carts/1
Pragmatic Bookshelf
Your Pragmatic Cart
- 2 × Programming Ruby 1.9 & 2.0
Fill in the self.down method
edit db/migrate/20140923000005_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
== 20140923000005 CombineItemsInCart: reverting ===============================
== 20140923000005 CombineItemsInCart: reverted (0.0098s) ======================
rake db:migrate:status
database: /home/rubys/git/awdwr/edition4/work-210/depot/db/development.sqlite3
Status Migration ID Migration Name
--------------------------------------------------
up 20140923000001 Create products
up 20140923000002 Create carts
up 20140923000003 Create line items
up 20140923000004 Add quantity to line items
down 20140923000005 Combine items in cart
mv db/migrate/20140923000005_combine_items_in_cart.rb db/migrate/20140923000005_combine_items_in_cart.bak
Every item should (once again) only have a quantity of one.
get /carts/1
Pragmatic Bookshelf
Your Pragmatic Cart
- 1 × Programming Ruby 1.9 & 2.0
- 1 × Programming Ruby 1.9 & 2.0
Recombine the item data.
mv db/migrate/20140923000005_combine_items_in_cart.bak db/migrate/20140923000005_combine_items_in_cart.rb
rake db:migrate
== 20140923000005 CombineItemsInCart: migrating ===============================
== 20140923000005 CombineItemsInCart: migrated (0.0227s) ======================
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 & 2.0
- 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 & 2.0
- 1 × CoffeeScript
Try something malicious.
get /carts/wibble
ActiveRecord::RecordNotFound
in CartsController#show
Couldn't find Cart with 'id'=wibble
Extracted source (around line #150):
148
149
150
151
152
153
|
record = s.execute([id], self, connection).first
unless record
raise RecordNotFound, "Couldn't find #{name} with '#{primary_key}'=#{id}"
end
record
end
|
Extracted source (around line #67):
65
66
67
68
69
70
|
# Use callbacks to share common setup or constraints between actions.
def set_cart
@cart = Cart.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
|
Extracted source (around line #424):
422
423
424
425
426
427
|
case filter
when Symbol
lambda { |target, _, &blk| target.send filter, &blk }
when String
l = eval "lambda { |value| #{filter} }"
lambda { |target, value| target.instance_exec(value, &l) }
|
Extracted source (around line #142):
140
141
142
143
144
145
|
if !halted && user_conditions.all? { |c| c.call(target, value) }
result = user_callback.call target, value
env.halted = halted_lambda.call(target, result)
if env.halted
target.send :halted_callback_hook, filter
|
Extracted source (around line #142):
140
141
142
143
144
145
|
if !halted && user_conditions.all? { |c| c.call(target, value) }
result = user_callback.call target, value
env.halted = halted_lambda.call(target, result)
if env.halted
target.send :halted_callback_hook, filter
|
Extracted source (around line #231):
229
230
231
232
233
234
|
def self.halting(next_callback, user_callback)
lambda { |env|
env = next_callback.call env
unless env.halted
user_callback.call env.target, env.value
end
|
Extracted source (around line #231):
229
230
231
232
233
234
|
def self.halting(next_callback, user_callback)
lambda { |env|
env = next_callback.call env
unless env.halted
user_callback.call env.target, env.value
end
|
Extracted source (around line #231):
229
230
231
232
233
234
|
def self.halting(next_callback, user_callback)
lambda { |env|
env = next_callback.call env
unless env.halted
user_callback.call env.target, env.value
end
|
Extracted source (around line #231):
229
230
231
232
233
234
|
def self.halting(next_callback, user_callback)
lambda { |env|
env = next_callback.call env
unless env.halted
user_callback.call env.target, env.value
end
|
Extracted source (around line #166):
164
165
166
167
168
169
|
end
end
next_callback.call env
}
end
private_class_method :halting
|
Extracted source (around line #166):
164
165
166
167
168
169
|
end
end
next_callback.call env
}
end
private_class_method :halting
|
Extracted source (around line #166):
164
165
166
167
168
169
|
end
end
next_callback.call env
}
end
private_class_method :halting
|
Extracted source (around line #166):
164
165
166
167
168
169
|
end
end
next_callback.call env
}
end
private_class_method :halting
|
Extracted source (around line #231):
229
230
231
232
233
234
|
def self.halting(next_callback, user_callback)
lambda { |env|
env = next_callback.call env
unless env.halted
user_callback.call env.target, env.value
end
|
Extracted source (around line #231):
229
230
231
232
233
234
|
def self.halting(next_callback, user_callback)
lambda { |env|
env = next_callback.call env
unless env.halted
user_callback.call env.target, env.value
end
|
Extracted source (around line #166):
164
165
166
167
168
169
|
end
end
next_callback.call env
}
end
private_class_method :halting
|
Extracted source (around line #166):
164
165
166
167
168
169
|
end
end
next_callback.call env
}
end
private_class_method :halting
|
Extracted source (around line #87):
85
86
87
88
89
90
|
runner = cbs.compile
e = Filters::Environment.new(self, false, nil, block)
runner.call(e).value
end
end
|
Extracted source (around line #87):
85
86
87
88
89
90
|
runner = cbs.compile
e = Filters::Environment.new(self, false, nil, block)
runner.call(e).value
end
end
|
Extracted source (around line #19):
17
18
19
20
21
22
|
# process_action callbacks around the normal behavior.
def process_action(*args)
run_callbacks(:process_action) do
super
end
end
|
Extracted source (around line #29):
27
28
29
30
31
32
|
private
def process_action(*args)
super
rescue Exception => exception
request.env['action_dispatch.show_detailed_exceptions'] ||= show_detailed_exceptions?
rescue_with_handler(exception) || raise(exception)
|
Extracted source (around line #31):
29
30
31
32
33
34
|
ActiveSupport::Notifications.instrument("process_action.action_controller", raw_payload) do |payload|
result = super
payload[:status] = response.status
append_info_to_payload(payload)
result
|
Extracted source (around line #164):
162
163
164
165
166
167
|
def instrument(name, payload = {})
if notifier.listening?(name)
instrumenter.instrument(name, payload) { yield payload if block_given? }
else
yield payload if block_given?
end
|
Extracted source (around line #20):
18
19
20
21
22
23
|
start name, payload
begin
yield payload
rescue Exception => e
payload[:exception] = [e.class.name, e.message]
raise e
|
Extracted source (around line #164):
162
163
164
165
166
167
|
def instrument(name, payload = {})
if notifier.listening?(name)
instrumenter.instrument(name, payload) { yield payload if block_given? }
else
yield payload if block_given?
end
|
Extracted source (around line #30):
28
29
30
31
32
33
|
ActiveSupport::Notifications.instrument("start_processing.action_controller", raw_payload.dup)
ActiveSupport::Notifications.instrument("process_action.action_controller", raw_payload) do |payload|
result = super
payload[:status] = response.status
append_info_to_payload(payload)
|
Extracted source (around line #250):
248
249
250
251
252
253
|
request.filtered_parameters.merge! wrapped_filtered_hash
end
super
end
private
|
Extracted source (around line #18):
16
17
18
19
20
21
|
# and it won't be cleaned up by the method below.
ActiveRecord::LogSubscriber.reset_runtime
super
end
def cleanup_view_runtime
|
Extracted source (around line #137):
135
136
137
138
139
140
|
@_response_body = nil
process_action(action_name, *args)
end
# Delegates to the class' #controller_path
|
Extracted source (around line #30):
28
29
30
31
32
33
|
def process(*) #:nodoc:
old_config, I18n.config = I18n.config, I18nProxy.new(I18n.config, lookup_context)
super
ensure
I18n.config = old_config
end
|
Extracted source (around line #195):
193
194
195
196
197
198
|
@_env = request.env
@_env['action_controller.instance'] = self
process(name)
to_a
end
|
Extracted source (around line #13):
11
12
13
14
15
16
|
def dispatch(action, request)
set_response!(request)
super(action, request)
end
def response_body=(body)
|
Extracted source (around line #236):
234
235
236
237
238
239
|
end
else
lambda { |env| new.dispatch(name, klass.new(env)) }
end
end
|
Extracted source (around line #72):
70
71
72
73
74
75
|
def dispatch(controller, action, env)
controller.action(action).call(env)
end
def normalize_controller!(params)
|
Extracted source (around line #72):
70
71
72
73
74
75
|
def dispatch(controller, action, env)
controller.action(action).call(env)
end
def normalize_controller!(params)
|
Extracted source (around line #41):
39
40
41
42
43
44
|
end
dispatch(controller, params[:action], req.env)
end
def prepare_params!(params)
|
Extracted source (around line #43):
41
42
43
44
45
46
|
req.path_parameters = set_params.merge parameters
status, headers, body = route.app.serve(req)
if 'pass' == headers['X-Cascade']
req.script_name = script_name
|
Extracted source (around line #30):
28
29
30
31
32
33
|
def serve(req)
find_routes(req).each do |match, parameters, route|
set_params = req.path_parameters
path_info = req.path_info
script_name = req.script_name
|
Extracted source (around line #30):
28
29
30
31
32
33
|
def serve(req)
find_routes(req).each do |match, parameters, route|
set_params = req.path_parameters
path_info = req.path_info
script_name = req.script_name
|
Extracted source (around line #750):
748
749
750
751
752
753
|
req = request_class.new(env)
req.path_info = Journey::Router::Utils.normalize_path(req.path_info)
@router.serve(req)
end
def recognize_path(path, environment = {})
|
Extracted source (around line #23):
21
22
23
24
25
26
|
def call(env)
status, headers, body = @app.call(env)
if etag_status?(status) && etag_body?(body) && !skip_caching?(headers)
original_body = body
|
Extracted source (around line #25):
23
24
25
26
27
28
|
case env['REQUEST_METHOD']
when "GET", "HEAD"
status, headers, body = @app.call(env)
headers = Utils::HeaderHash.new(headers)
if status == 200 && fresh?(env, headers)
status = 304
|
Extracted source (around line #13):
11
12
13
14
15
16
|
def call(env)
status, headers, body = @app.call(env)
if env["REQUEST_METHOD"] == "HEAD"
[
|
Extracted source (around line #27):
25
26
27
28
29
30
|
end
@app.call(env)
end
private
|
Extracted source (around line #257):
255
256
257
258
259
260
|
def call(env)
@app.call(env)
ensure
session = Request::Session.find(env) || {}
flash_hash = env[KEY]
|
Extracted source (around line #225):
223
224
225
226
227
228
|
def context(env, app=@app)
prepare_session(env)
status, headers, body = app.call(env)
commit_session(env, status, headers, body)
end
|
Extracted source (around line #220):
218
219
220
221
222
223
|
def call(env)
context(env)
end
def context(env, app=@app)
|
Extracted source (around line #558):
556
557
558
559
560
561
|
def call(env)
status, headers, body = @app.call(env)
if cookie_jar = env['action_dispatch.cookies']
unless cookie_jar.committed?
|
Extracted source (around line #36):
34
35
36
37
38
39
|
connection.enable_query_cache!
response = @app.call(env)
response[2] = Rack::BodyProxy.new(response[2]) do
restore_query_cache_settings(connection_id, enabled)
end
|
Extracted source (around line #645):
643
644
645
646
647
648
|
testing = env.key?('rack.test')
response = @app.call(env)
response[2] = ::Rack::BodyProxy.new(response[2]) do
ActiveRecord::Base.clear_active_connections! unless testing
end
|
Extracted source (around line #378):
376
377
378
379
380
381
|
end
end
@app.call(env)
end
private
|
Extracted source (around line #29):
27
28
29
30
31
32
|
result = run_callbacks :call do
begin
@app.call(env)
rescue => error
end
end
|
Extracted source (around line #83):
81
82
83
84
85
86
|
cbs = send("_#{kind}_callbacks")
if cbs.empty?
yield if block_given?
else
runner = cbs.compile
e = Filters::Environment.new(self, false, nil, block)
|
Extracted source (around line #27):
25
26
27
28
29
30
|
def call(env)
error = nil
result = run_callbacks :call do
begin
@app.call(env)
rescue => error
|
Extracted source (around line #73):
71
72
73
74
75
76
|
prepare!
response = @app.call(env)
response[2] = ::Rack::BodyProxy.new(response[2]) { cleanup! }
response
|
Extracted source (around line #78):
76
77
78
79
80
81
|
def call(env)
env["action_dispatch.remote_ip"] = GetIp.new(env, self)
@app.call(env)
end
# The GetIp class exists as a way to defer processing of the request data
|
Extracted source (around line #18):
16
17
18
19
20
21
|
def middleware_call(env)
_, headers, body = response = @app.call(env)
if headers['X-Cascade'] == 'pass'
body.close if body.respond_to?(:close)
|
Extracted source (around line #13):
11
12
13
14
15
16
|
change_stack_trace(m[:id], request.params[:frame_id])
else
middleware_call(env)
end
end
|
Extracted source (around line #30):
28
29
30
31
32
33
|
def call(env)
@app.call(env)
rescue Exception => exception
if env['action_dispatch.show_exceptions'] == false
raise exception
|
Extracted source (around line #38):
36
37
38
39
40
41
|
instrumenter.start 'request.action_dispatch', request: request
logger.info { started_request_message(request) }
resp = @app.call(env)
resp[2] = ::Rack::BodyProxy.new(resp[2]) { finish(request) }
resp
rescue Exception
|
Extracted source (around line #20):
18
19
20
21
22
23
|
if logger.respond_to?(:tagged)
logger.tagged(compute_tags(request)) { call_app(request, env) }
else
call_app(request, env)
end
|
Extracted source (around line #68):
66
67
68
69
70
71
|
def tagged(*tags)
formatter.tagged(*tags) { yield self }
end
def flush
|
Extracted source (around line #26):
24
25
26
27
28
29
|
def tagged(*tags)
new_tags = push_tags(*tags)
yield self
ensure
pop_tags(new_tags.size)
end
|
Extracted source (around line #68):
66
67
68
69
70
71
|
def tagged(*tags)
formatter.tagged(*tags) { yield self }
end
def flush
|
Extracted source (around line #20):
18
19
20
21
22
23
|
if logger.respond_to?(:tagged)
logger.tagged(compute_tags(request)) { call_app(request, env) }
else
call_app(request, env)
end
|
Extracted source (around line #21):
19
20
21
22
23
24
|
def call(env)
env["action_dispatch.request_id"] = external_request_id(env) || internal_request_id
@app.call(env).tap { |_status, headers, _body| headers["X-Request-Id"] = env["action_dispatch.request_id"] }
end
private
|
Extracted source (around line #22):
20
21
22
23
24
25
|
end
@app.call(env)
end
def method_override(env)
|
Extracted source (around line #17):
15
16
17
18
19
20
|
def call(env)
start_time = Time.now
status, headers, body = @app.call(env)
request_time = Time.now - start_time
if !headers.has_key?(@header_name)
|
Extracted source (around line #28):
26
27
28
29
30
31
|
def call(env)
LocalCacheRegistry.set_cache_for(local_cache_key, LocalStore.new)
response = @app.call(env)
response[2] = ::Rack::BodyProxy.new(response[2]) do
LocalCacheRegistry.set_cache_for(local_cache_key, nil)
end
|
Extracted source (around line #17):
15
16
17
18
19
20
|
old, env[FLAG] = env[FLAG], false
@mutex.lock
response = @app.call(env)
body = BodyProxy.new(response[2]) { @mutex.unlock }
response[2] = body
response
|
Extracted source (around line #103):
101
102
103
104
105
106
|
end
@app.call(env)
end
end
end
|
Extracted source (around line #113):
111
112
113
114
115
116
|
def call(env)
status, headers, body = @app.call(env)
if body.respond_to?(:to_path)
case type = variation(env)
when 'X-Accel-Redirect'
|
Extracted source (around line #514):
512
513
514
515
516
517
|
env["ROUTES_#{routes.object_id}_SCRIPT_NAME"] = env['SCRIPT_NAME'].dup
end
app.call(env)
end
# Defines additional Rack env configuration that is added on each call.
|
Extracted source (around line #161):
159
160
161
162
163
164
|
env["ORIGINAL_FULLPATH"] = build_original_fullpath(env)
env["ORIGINAL_SCRIPT_NAME"] = env["SCRIPT_NAME"]
super(env)
end
# Reload application routes regardless if they changed or not.
|
Extracted source (around line #15):
13
14
15
16
17
18
|
def call(env)
env['rack.tempfiles'] ||= []
status, headers, body = @app.call(env)
body_proxy = BodyProxy.new(body) do
env['rack.tempfiles'].each { |f| f.close! } unless env['rack.tempfiles'].nil?
end
|
Extracted source (around line #49):
47
48
49
50
51
52
|
## and returns an Array of exactly three values:
status, headers, @body = @app.call(env)
## The *status*,
check_status status
## the *headers*,
|
Extracted source (around line #37):
35
36
37
38
39
40
|
## responds to +call+.
def call(env=nil)
dup._call(env)
end
def _call(env)
|
Extracted source (around line #24):
22
23
24
25
26
27
|
def call(env)
@app.call(env)
rescue StandardError, LoadError, SyntaxError => e
exception_string = dump_exception(e)
|
Extracted source (around line #33):
31
32
33
34
35
36
|
def call(env)
began_at = Time.now
status, header, body = @app.call(env)
header = Utils::HeaderHash.new(header)
body = BodyProxy.new(body) { log(env, status, header, began_at) }
[status, header, body]
|
Extracted source (around line #54):
52
53
54
55
56
57
|
def call(env)
status, headers, body = @app.call(env)
headers = HeaderHash.new(headers)
if ! chunkable_version?(env['HTTP_VERSION']) ||
|
Extracted source (around line #15):
13
14
15
16
17
18
|
def call(env)
status, headers, body = @app.call(env)
headers = HeaderHash.new(headers)
if !STATUS_WITH_NO_ENTITY_BODY.include?(status.to_i) &&
|
Extracted source (around line #89):
87
88
89
90
91
92
|
env["REQUEST_PATH"] ||= [env["SCRIPT_NAME"], env["PATH_INFO"]].join
status, headers, body = @app.call(env)
begin
res.status = status.to_i
headers.each { |k, vs|
|
Extracted source (around line #138):
136
137
138
139
140
141
|
si = servlet.get_instance(self, *options)
@logger.debug(format("%s is invoked.", si.class.name))
si.service(req, res)
end
##
|
Extracted source (around line #94):
92
93
94
95
96
97
|
callback.call(req, res)
end
server.service(req, res)
rescue HTTPStatus::EOFError, HTTPStatus::RequestTimeout => ex
res.set_error(ex)
rescue HTTPStatus::Error => ex
|
Extracted source (around line #295):
293
294
295
296
297
298
|
end
call_callback(:AcceptCallback, sock)
block ? block.call(sock) : run(sock)
rescue Errno::ENOTCONN
@logger.debug "Errno::ENOTCONN raised"
rescue ServerError => ex
|
Rails.root: /home/rubys/git/awdwr/edition4/work-210/depot
Request
Parameters:
{"id"=>"wibble"}
_csrf_token: "TGDhImSdn9cfu4tvRF3Y0qjHtmgmsGUWG7BloHrny4w="
cart_id: 1
flash: {"discard"=>["notice"], "flashes"=>{"notice"=>"Line item was successfully created."}}
session_id: "aadf44f38ebb83959e894aa297fc066d"
GATEWAY_INTERFACE: "CGI/1.1"
HTTP_ACCEPT: "text/html"
HTTP_ACCEPT_ENCODING: "gzip;q=1.0,deflate;q=0.6,identity;q=0.3"
REMOTE_ADDR: "127.0.0.1"
REMOTE_HOST: "127.0.0.1"
SERVER_NAME: "localhost"
SERVER_PROTOCOL: "HTTP/1.1"
Response
Headers:
None
10.2 Iteration E2: Handling Errors
9.4 Playtime