Staying railsy - while scaling complexity. Making Ruby on rails excel in complex software applications.

1. Rails in the
Enterprise Staying Railsy
while scaling complexity

2. David Williams
@metakube

4. Of all the terms I hate with a passion,
“professional” would probably rank
above “enterprise” and just below
“potty mouth”.
–@dhh in 2009

5. What does
ENTERPRISE
mean?

6. EDI
Workflow
XML
SOAP
COBOL
BPEL ABAP/4

7. automation
visibility
compliance

8. it comes down to
$

9. But we’re software people.
Start talking tech.
–y’all, just now

10. COMPLEXITY

11. What does
COMPLEXITY
mean?

12. 5 languages
14 standard user roles
166 controllers
183 database tables
1577 permissions
58k lines of code
>100k API calls / day
3m rows in biggest table
$5.6b spend through system

13. Internationalization
Localization
XSS protection
Single sign-on
Data security
Extensibility
Customization
API integration
S*@P

14. co sta
m te
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pl m
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qu i
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er ne
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RU
LE

15. co sta
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pl m
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ex a t
m ac
ch
xo
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qu i
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er ne
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RU
LE

16. Pointcuts
Cross Cutting Concerns
Decorator Pattern
Aspect Oriented
Programming
Adapter Pattern
Separation of Concerns
Multiple Inheritance

17. Mixins

18. class RequisitionHeader
< ActiveRecord::Base
has_custom_fields
acts_as_revisionable
securable_by_account
api_in
api_out
end

19. class RequisitionHeader
< ActiveRecord::Base
has_custom_fields
acts_as_revisionable
securable_by_account
api_in
Let’s talk about these
api_out
end

20. co sta
m te
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pl m
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ex a t
m ac
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xo
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qu i
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RU
LE
S

21. I♥
ruby

24. class Api::DepartmentsController
< Api::BaseController
api_scaffold :department
end
Coupa::Application.routes.draw do
namespace :api do
resources :departments
end
end

25. class Department
< ActiveRecord::Base
api_in [:name, :active], [],
{:keys => ["id", "name"]}
api_out [:name, :active]
end

26. (lack of)
class Department associations
< ActiveRecord::Base
api_in [:name, :active], [],
{:keys => ["id", "name"]}
api_out [:name, :active]
end

27. (lack of)
class Department associations
< ActiveRecord::Base
api_in [:name, :active], [],
{:keys => ["id", "name"]}
api_out [:name, :active]
end

28. class Api::BaseController < AppController
def self.api_scaffold(model_id, options={})
options.assert_valid_keys(:class_name,
:scope, :user_scope, :validate_if,
:before_save)
singular_name = model_id.to_s
class_name = options[:class_name] ||
singular_name.camelize
model_class = class_name.constantize
[way more code than I can fit]
self.module_eval(overlay_methods)
end
end

29. APIs and...

30. APIs and... bulk loaders
custom fields
searchable table views
budgeting
approval workflows
revision tracking
reporting
notifications
caching
and more...

31. co sta
m te
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pl m
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ex a t
m ac
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xo
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qu i
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RU
LE

34. We use AASM*
* Monkeypatched for transactional error handling,
and for the event transitions to work like they used
to.

35. class RequisitionHeader < ActiveRecord::Base
state :pending_buyer_action,
:enter => Proc.new { |r|
Notifier.req_requires_action(r) }
state :pending_approval,
:after_enter => Proc.new { |r|
ApprovalNotify.next_approver(r)}
state :ordered,
:enter => Proc.new { |r|
OrderHeader.create_from_req(r) }
end

36. class RequisitionHeader < ActiveRecord::Base
state :pending_buyer_action,
:enter => Proc.new { |r|
Notifier.req_requires_action(r) }
state :pending_approval,
:after_enter => Proc.new { |r|
ApprovalNotify.next_approver(r) }
state :ordered,
:enter => Proc.new { |r|
OrderHeader.create_from_req(r) }
end

37. class RequisitionHeader < ActiveRecord::Base
event :submit_for_approval do
transitions :to => :pending_approval,
:from => [:draft, :cart],
:guard => :approvable?
transitions :to => :pending_buyer_action,
:from => [:draft, :cart],
:guard => :submittable?
end
end

38. class RequisitionHeader < ActiveRecord::Base
event :submit_for_approval do
transitions :to => :pending_approval,
:from => [:draft, :cart],
:guard => :approvable?
transitions :to => :pending_buyer_action,
:from => [:draft, :cart],
:guard => :submittable?
end
end

39. class RequisitionHeader < ActiveRecord::Base
event :submit_for_approval do
transitions :to => :pending_approval,
:from => [:draft, :cart],
:guard => :approvable?
transitions :to => :pending_buyer_action,
:from => [:draft, :cart],
:guard => :submittable?
end
end

40. What’s the point?

41. class RequisitionHeader < ActiveRecord::Base
validates_presence_of :ship_to_address,
:if => Proc.new { |requisition_header|
requisition_header.status &&
!%w(draft cart pending_buyer_action).
include?(requisition_header.status)
}
end

42. class RequisitionHeader < ActiveRecord::Base
def editable?
user = User.current_user
case self.status
when 'pending_approval'
approvable_by? && user && user.authorized?('approver', 'edit')
when 'cart', 'draft'
user == self.requested_by || user == self.created_by
when 'pending_buyer_action'
user && user.authorized?('buying', 'edit')
else
false
end
end
end

43. Yawn. Show me a hack.
–y’all, just now

44. I18n loose end tying: Ugly but useful
module ActiveSupport::Inflector
def humanize_with_translation(underscored_word)
begin
(I18n.translate!("statuses.#{underscored_word}",
:default => :"activerecord.models.#{underscored_word}",
:count => 1) unless underscored_word.blank?) || ''
rescue I18n::MissingTranslationData => e
humanize_without_translation(underscored_word)
end
end
alias_method_chain :humanize, :translation
end

45. co sta
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qu i
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RU
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46. IF YOU TREAT YOUR DB AS DUMB
HOW CAN IT LOVE YOU?

47. SELECT distinct suppliers.id
FROM suppliers
JOIN supplier_items ON supplier_items.supplier_id = suppliers.id
LEFT OUTER JOIN catalogs ON catalogs.id = supplier_items.catalog_id
LEFT OUTER JOIN contracts ON contracts.id =
supplier_items.contract_id
LEFT OUTER JOIN business_group_assignments ON
(business_group_assignments.securable_id = contracts.id AND
business_group_assignments.securable_type = 'Contract')
STRAIGHT_JOIN items ON (items.id = supplier_items.item_id AND
items.active = 1 AND (items.connect_item_id IS NULL OR
items.imported_from_connect = 1))
WHERE ( suppliers.status = 'active'
AND (supplier_items.catalog_id IS NULL
OR ( catalogs.status = 'accepted'
AND (catalogs.start_date IS NULL OR '2011-11-15 18:30:00' >=
catalogs.start_date)
AND (catalogs.end_date IS NULL OR '2011-11-15 18:30:00' <
catalogs.end_date) ))
AND (supplier_items.contract_id IS NULL
OR (contracts.status = 'published'
AND business_group_assignments.business_group_id in (3,2,1)
AND contracts.start_date <= '2011-11-15 18:30:00'
AND (contracts.end_date IS NULL OR contracts.end_date > '2011-11-15
18:30:00') ))

48. SELECT distinct suppliers.id
FROM suppliers
sy
JOIN supplier_items ON supplier_items.supplier_id = suppliers.id
LEFT OUTER JOIN catalogs ON catalogs.id = supplier_items.catalog_id
LEFT OUTER JOIN contracts ON contracts.id =
il
supplier_items.contract_id
LEFT OUTER JOIN business_group_assignments ON
(business_group_assignments.securable_id = contracts.id AND
Ra
business_group_assignments.securable_type = 'Contract')
STRAIGHT_JOIN items ON (items.id = supplier_items.item_id AND
items.active = 1 AND (items.connect_item_id IS NULL OR
items.imported_from_connect = 1))
ry
WHERE ( suppliers.status = 'active'
AND (supplier_items.catalog_id IS NULL
OR ( catalogs.status = 'accepted'
AND (catalogs.start_date IS NULL OR '2011-11-15 18:30:00' >=
ve
catalogs.start_date)
AND (catalogs.end_date IS NULL OR '2011-11-15 18:30:00' <
catalogs.end_date) ))
AND (supplier_items.contract_id IS NULL
OR (contracts.status = 'published'
t
AND business_group_assignments.business_group_id in (3,2,1)
No
AND contracts.start_date <= '2011-11-15 18:30:00'
AND (contracts.end_date IS NULL OR contracts.end_date > '2011-11-15
18:30:00') ))

49. So let’s step back a moment and
talk about a common problem...

50. Displaying paginated
search results

52. What you’re querying on doesn’t
always match what you’re
displaying

53. Users Roles Permissions
Suppliers Addresses Countries
Commodities Contacts
And this is a
simple one...

54. Users Roles Permissions
Online Shipping Payment
Stores Terms Terms
Suppliers Addresses Countries
Parent Phone
Suppliers Numbers
Commodities Contacts
And this is a
simple one...

55. outer join != :include

56. Depends on a Ruby monkeypatch
.joins(begin
options[:include].deep_exec{|c|
c.to_sym.send(:outer)
}
rescue
[]
end)
Depends on Ernie Miller’s awesome
Metawhere / Squeel

57. Wow, that’s nasty.
Why would you do that?
–y’all, just now

59. 30% improvement in common cases

60. 30% improvement in common cases
90% improvement in some nasty cases

61. 30% improvement in common cases
90% improvement in some nasty cases
YMMV

62. MySQL doesn’t ♥ sorting

63. Narrow your SELECT clauses

64. .paginate({
:select => 'SQL_CALC_FOUND_ROWS
DISTINCT #{table}.id',
:per_page => 20,
:page => options[:page]
})

65. MySQL count query avoidance hack. YMMV.
.paginate({
:select => 'SQL_CALC_FOUND_ROWS
DISTINCT #{table}.id',
:per_page => 20,
:page => options[:page]
})

66. MySQL count query avoidance hack. YMMV.
.paginate({
:select => 'SQL_CALC_FOUND_ROWS
DISTINCT #{table}.id',
:per_page => 20,
:page => options[:page]
})
[Then query just the rows you want]

67. Like deep_clone? Try deep_exec.
class Array
def deep_exec(&blk)
result = []
each do |e|
if e.respond_to?(:deep_exec)
result << e.deep_exec(&blk)
else
result << yield(e)
end
end
result
end
end

68. Like deep_clone? Try deep_exec.
class Array class Hash
def deep_exec(&blk)
def deep_exec(&blk)
result = {}
result = []
each do |k,v|
each do |e|
result[yield k] =
if e.respond_to?(:deep_exec)
if v.respond_to?(:deep_exec)
result << e.deep_exec(&blk)
v.deep_exec(&blk)
else
else
result << yield(e)
yield v
end
end
end
end
result
result
end
end
end
end

69. Totally out of time...

70. We’re Hiring!
(I know, total surprise.)

71. Photo Credits
Used under Creative Commons from typedow
Used under Creative Commons from gaymerbear
Used under Creative Commons from Mandy_Jansen
http://popartmachine.com/blog/pop-art-based-on-hawaiian-shirt-pattern.html
Used under Creative Commons from casey.marshall