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/20170602134112_add_quantity_to_line_items.rb
Modify the migration to add a default value for the new column
edit db/migrate/20170602134112_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 20170602134112_add_quantity_to_line_items.rb 20170602000004_add_quantity_to_line_items.rb
== 20170602000004 AddQuantityToLineItems: migrating ===========================
-- add_column(:line_items, :quantity, :integer, {:default=>1})
-> 0.0005s
== 20170602000004 AddQuantityToLineItems: migrated (0.0005s) ==================
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)
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)
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
<p id="notice"><%= notice %></p>
<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
Your Pragmatic Cart
- 1 × Seven Mobile Apps in Seven Weeks
- 1 × Seven Mobile Apps in Seven Weeks
Generate a migration to combine/separate items in carts.
rails generate migration combine_items_in_cart
invoke active_record
create db/migrate/20170602134114_combine_items_in_cart.rb
Fill in the self.up method
edit db/migrate/20170602134114_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 20170602134114_combine_items_in_cart.rb 20170602000005_combine_items_in_cart.rb
== 20170602000005 CombineItemsInCart: migrating ===============================
== 20170602000005 CombineItemsInCart: migrated (0.0234s) ======================
Verify that the entries have been combined.
get /carts/1
Your Pragmatic Cart
- 2 × Seven Mobile Apps in Seven Weeks
Fill in the self.down method
edit db/migrate/20170602000005_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
== 20170602000005 CombineItemsInCart: reverting ===============================
== 20170602000005 CombineItemsInCart: reverted (0.0089s) ======================
rake db:migrate:status
database: /home/rubys/git/awdwr/edition4/work-226-42/depot/db/development.sqlite3
Status Migration ID Migration Name
--------------------------------------------------
up 20170602000001 Create products
up 20170602000002 Create carts
up 20170602000003 Create line items
up 20170602000004 Add quantity to line items
down 20170602000005 Combine items in cart
mv db/migrate/20170602000005_combine_items_in_cart.rb db/migrate/20170602000005_combine_items_in_cart.bak
Every item should (once again) only have a quantity of one.
get /carts/1
Your Pragmatic Cart
- 1 × Seven Mobile Apps in Seven Weeks
- 1 × Seven Mobile Apps in Seven Weeks
Recombine the item data.
mv db/migrate/20170602000005_combine_items_in_cart.bak db/migrate/20170602000005_combine_items_in_cart.rb
rake db:migrate
== 20170602000005 CombineItemsInCart: migrating ===============================
== 20170602000005 CombineItemsInCart: migrated (0.0232s) ======================
Add a few products to the order.
post /line_items?product_id=2
You are being
redirected.
get http://localhost:3000/carts/1
Line item was successfully created.
Your Pragmatic Cart
- 2 × Seven Mobile Apps in Seven Weeks
- 1 × Rails, Angular, Postgres, and Bootstrap
post /line_items?product_id=3
You are being
redirected.
get http://localhost:3000/carts/1
Line item was successfully created.
Your Pragmatic Cart
- 3 × Seven Mobile Apps in Seven Weeks
- 1 × Rails, Angular, Postgres, and Bootstrap
Try something malicious.
get /carts/wibble
HTTP Response Code: 404
ActiveRecord::RecordNotFound
in CartsController#show
Couldn't find Cart with 'id'=wibble
Extracted source (around line #155):
153
154
155
156
157
158
|
record = s.execute([id], self, connection).first
unless record
raise RecordNotFound, "Couldn't find #{name} with '#{primary_key}'=#{id}"
end
record
rescue RangeError
|
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 #432):
430
431
432
433
434
435
|
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 #145):
143
144
145
146
147
148
|
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 #145):
143
144
145
146
147
148
|
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 #504):
502
503
504
505
506
507
|
def call(*args)
@before.each { |b| b.call(*args) }
value = @call.call(*args)
@after.each { |a| a.call(*args) }
value
|
Extracted source (around line #504):
502
503
504
505
506
507
|
def call(*args)
@before.each { |b| b.call(*args) }
value = @call.call(*args)
@after.each { |a| a.call(*args) }
value
|
Extracted source (around line #504):
502
503
504
505
506
507
|
def call(*args)
@before.each { |b| b.call(*args) }
value = @call.call(*args)
@after.each { |a| a.call(*args) }
value
|
Extracted source (around line #504):
502
503
504
505
506
507
|
def call(*args)
@before.each { |b| b.call(*args) }
value = @call.call(*args)
@after.each { |a| a.call(*args) }
value
|
Extracted source (around line #92):
90
91
92
93
94
95
|
runner = callbacks.compile
e = Filters::Environment.new(self, false, nil, block)
runner.call(e).value
end
end
|
Extracted source (around line #778):
776
777
778
779
780
781
|
module_eval <<-RUBY, __FILE__, __LINE__ + 1
def _run_#{name}_callbacks(&block)
__run_callbacks__(_#{name}_callbacks, &block)
end
RUBY
end
|
Extracted source (around line #81):
79
80
81
82
83
84
|
# end
def run_callbacks(kind, &block)
send "_run_#{kind}_callbacks", &block
end
private
|
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 #32):
30
31
32
33
34
35
|
ActiveSupport::Notifications.instrument("process_action.action_controller", raw_payload) do |payload|
begin
result = super
payload[:status] = response.status
result
ensure
|
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|
begin
result = super
payload[:status] = response.status
|
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 #196):
194
195
196
197
198
199
|
@_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 #237):
235
236
237
238
239
240
|
end
else
lambda { |env| new.dispatch(name, klass.new(env)) }
end
end
end
|
Extracted source (around line #74):
72
73
74
75
76
77
|
def dispatch(controller, action, env)
controller.action(action).call(env)
end
def normalize_controller!(params)
|
Extracted source (around line #74):
72
73
74
75
76
77
|
def dispatch(controller, action, env)
controller.action(action).call(env)
end
def normalize_controller!(params)
|
Extracted source (around line #43):
41
42
43
44
45
46
|
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 #817):
815
816
817
818
819
820
|
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 #24):
22
23
24
25
26
27
|
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 #260):
258
259
260
261
262
263
|
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 #560):
558
559
560
561
562
563
|
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 #653):
651
652
653
654
655
656
|
testing = env['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 #377):
375
376
377
378
379
380
|
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 #88):
86
87
88
89
90
91
|
def __run_callbacks__(callbacks, &block)
if callbacks.empty?
yield if block_given?
else
runner = callbacks.compile
e = Filters::Environment.new(self, false, nil, block)
|
Extracted source (around line #778):
776
777
778
779
780
781
|
module_eval <<-RUBY, __FILE__, __LINE__ + 1
def _run_#{name}_callbacks(&block)
__run_callbacks__(_#{name}_callbacks, &block)
end
RUBY
end
|
Extracted source (around line #81):
79
80
81
82
83
84
|
# end
def run_callbacks(kind, &block)
send "_run_#{kind}_callbacks", &block
end
private
|
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 #17):
15
16
17
18
19
20
|
def call(env)
_, headers, body = response = @app.call(env)
if headers['X-Cascade'] == 'pass'
body.close if body.respond_to?(:close)
|
Extracted source (around line #28):
26
27
28
29
30
31
|
end
status, headers, body = @app.call(env)
if exception = env['web_console.exception']
session = Session.from_exception(exception)
|
Extracted source (around line #18):
16
17
18
19
20
21
|
def call(env)
app_exception = catch :app_exception do
request = create_regular_or_whiny_request(env)
return @app.call(env) unless request.from_whitelited_ip?
|
Extracted source (around line #18):
16
17
18
19
20
21
|
def call(env)
app_exception = catch :app_exception do
request = create_regular_or_whiny_request(env)
return @app.call(env) unless request.from_whitelited_ip?
|
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 #18):
16
17
18
19
20
21
|
def call(env)
start_time = clock_time
status, headers, body = @app.call(env)
request_time = clock_time - 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 #120):
118
119
120
121
122
123
|
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 #518):
516
517
518
519
520
521
|
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 #165):
163
164
165
166
167
168
|
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 #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 #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 #88):
86
87
88
89
90
91
|
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 #294):
292
293
294
295
296
297
|
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-226-42/depot
Request
Parameters:
{"id"=>"wibble"}
_csrf_token: "VOTK4hVhtLsD7nJymDi+8NRL/0RAeqGDk+Ks/kVVjek="
cart_id: 1
flash: {"discard"=>["notice"], "flashes"=>{"notice"=>"Line item was successfully created."}}
session_id: "e3a1a24539de2b8c87ec6b5b12104e70"
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
