Rails provides a set of conventions that allow you to rapidly develop new features, but what happens when things do not fit quite so nicely? Let’s discuss some alternative patterns that compliment Rails.

1. Beyond MVC
Kyle Rames
@krames

2. Conventions

3. app/model/store.rb

4. stores

5. db/migrate/
20140903103121_create
_store.rb

6. http://host/stores/edit

7. app/controller/
stores_controller.rb

8. app/views/store
app/helpers

10. Reduce Cognitive
Burden

11. What happens if the
action interacts with an
external service?

12. What happens when if
the action interacts with
multiple models?

13. How do we deal with
complex processes?

15. ?

16. /lib model
controller gem

17. Let’s talk about some
new patterns

18. Service Objects

19. Model Processes

20. 1 class UserAuthenticator
2 def initialize(user)
3 @user = user
4 end
5
6 def authenticate(unencrypted_password)
7 return false unless @user
8
9 if BCrypt::Password.new(@user.password_digest) ==
10 unencrypted_password
11 @user
12 else
13 false
14 end
15 end
16 end

21. 1 class UserAuthenticator
2 def initialize(user)
3 @user = user
4 end
5
6 def authenticate(unencrypted_password)
7 return false unless @user
8
9 if BCrypt::Password.new(@user.password_digest) ==
10 unencrypted_password
11 @user
12 else
13 false
14 end
15 end
16 end

22. 1 class UserAuthenticator
2 def initialize(user)
3 @user = user
4 end
5
6 def authenticate(unencrypted_password)
7 return false unless @user
8
9 if BCrypt::Password.new(@user.password_digest) ==
10 unencrypted_password
11 @user
12 else
13 false
14 end
15 end
16 end

23. 1 class SessionsController < ApplicationController
2 def create
3 user = User.where(email: params[:email]).first
4
5 if UserAuthenticator.new(user).
authenticate(params[:password])
6 self.current_user = user
7 redirect_to dashboard_path
8 else
9 flash[:alert] = "Login failed."
10 render "new"
11 end
12 end
13 end

24. 1 class SessionsController < ApplicationController
2 def create
3 user = User.where(email: params[:email]).first
4
5 if UserAuthenticator.new(user).
authenticate(params[:password])
6 self.current_user = user
7 redirect_to dashboard_path
8 else
9 flash[:alert] = "Login failed."
10 render "new"
11 end
12 end
13 end

25. Martin Fowler Says
The conceptual problem I run into in a lot
of codebases is that rather than
representing a process, the "service
objects" represent "a thing that does the
process".

26. Adding User
1. Create User
2. Collect Additional Information
3. Approve
4. Complete

27. 1 class UserAddition
2 def begin
3 # ...
4 end
5
6 def collect_extra_info
7 # ...
8 end
9
10 def approve
11 # ...
12 end
13
14 def complete
15 # ...
16 end
17 end

28. app/services

29. dhh says
Concerns

30. Form Objects

31. Model Stand-In

32. 1 class SignupForm
2 include ActiveModel::Model
3
4 validates_presence_of :email
5
6 delegate :name, :name= to: :company, prefix: true
7 delegate :name, :name=, :email, :email= to: :user
8
9 def company
10 @company ||= Company.new
11 end
12
13 def user
14 @user ||= company.build_user
15 end
16
17 def persisted?
18 false # Forms are never themselves persisted
19 end
20
21 def save
22 valid? ? persist!; true : false
23 end
24
25 private
26
27 def persist!
28 company.save && user.save
29 end
30 end

33. 1 class SignupForm
2 include ActiveModel::Model
3
4 validates_presence_of :email
5
6 delegate :name, :name= to: :company, prefix: true
7 delegate :name, :name=, :email, :email= to: :user
8
9 def company
10 @company ||= Company.new
11 end
12
13 def user
14 @user ||= company.build_user
15 end
16
17 def persisted?
18 false # Forms are never themselves persisted
19 end
20
21 def save
22 valid? ? persist!; true : false
23 end
24
25 private
26
27 def persist!
28 company.save && user.save
29 end
30 end

34. 1 class SignupForm
2 include ActiveModel::Model
3
4 validates_presence_of :email
5
6 delegate :name, :name= to: :company, prefix: true
7 delegate :name, :name=, :email, :email= to: :user
8
9 def company
10 @company ||= Company.new
11 end
12
13 def user
14 @user ||= company.build_user
15 end
16
17 def persisted?
18 false # Forms are never themselves persisted
19 end
20
21 def save
22 valid? ? persist!; true : false
23 end
24
25 private
26
27 def persist!
28 company.save && user.save
29 end
30 end

35. 1 class SignupForm
2 include ActiveModel::Model
3
4 validates_presence_of :email
5
6 delegate :name, :name= to: :company, prefix: true
7 delegate :name, :name=, :email, :email= to: :user
8
9 def company
10 @company ||= Company.new
11 end
12
13 def user
14 @user ||= company.build_user
15 end
16
17 def persisted?
18 false # Forms are never themselves persisted
19 end
20
21 def save
22 valid? ? persist!; true : false
23 end
24
25 private
26
27 def persist!
28 company.save && user.save
29 end
30 end

36. 1 class SignupsController < ApplicationController
2 def create
3 @signup = SignupForm.new(params[:signup_form])
4
5 if @signup.save
6 redirect_to dashboard_path
7 else
8 render "new"
9 end
10 end
11 end

37. 1 class SignupsController < ApplicationController
2 def create
3 @signup = SignupForm.new(params[:signup_form])
4
5 if @signup.save
6 redirect_to dashboard_path
7 else
8 render "new"
9 end
10 end
11 end

38. dhh says
accepts_nested_attributes_for

39. 1 class User < ActiveRecord::Base
2
3 validates_length_of :new_password,
4 minimum: 6,
5 if: :changing_password
6
7 ...
8 end

40. 1 class User < ActiveRecord::Base
2
3 validates_length_of :new_password,
4 minimum: 6,
5 if: :changing_password
6
7 ...
8 end

41. 1 class PasswordForm
2 include ActiveModel::Model
3
4 attr_accessor :original_password, :new_password
5
6 validate :verify_original_password
7 validates_presence_of :original_password, :new_password
8 validates_confirmation_of :new_password
9 validates_length_of :new_password, minimum: 6
10
11 def submit(params)
12 self.original_password = params[:original_password]
13 self.new_password = params[:new_password]
14 self.new_password_confirmation = params[
15 :new_password_confirmation]
16 if valid?
17 @user.password = new_password; @user.save; true
18 else
19 false
20 end
21 end
22
23 def initialize(user); @user = user; end
24 def persisted?; false; end
25 def verify_original_password; ...; end
26 end

42. 1 class PasswordForm
2 include ActiveModel::Model
3
4 attr_accessor :original_password, :new_password
5
6 validate :verify_original_password
7 validates_presence_of :original_password, :new_password
8 validates_confirmation_of :new_password
9 validates_length_of :new_password, minimum: 6
10
11 def submit(params)
12 self.original_password = params[:original_password]
13 self.new_password = params[:new_password]
14 self.new_password_confirmation = params[
15 :new_password_confirmation]
16 if valid?
17 @user.password = new_password; @user.save; true
18 else
19 false
20 end
21 end
22
23 def initialize(user); @user = user; end
24 def persisted?; false; end
25 def verify_original_password; ...; end
26 end

43. 1 class PasswordsController < ApplicationController
2 def new
3 @password_form = PasswordForm.new(current_user)
4 end
5
6 def create
7 @password_form = PasswordForm.new(current_user)
8 if @password_form.submit(params[:password_form])
9 redirect_to current_user, notice: “Success!"
10 else
11 render "new"
12 end
13 end
14 end

44. app/forms

45. Presenters

46. 1 <div id="profile">
2 <dl>
3 <dt>Username:</dt>
4 <dd><%= @user.username %></dd>
5 <dt>Member Since:</dt>
6 <dd><%= @user.member_since %></dd>
7 <dt>Website:</dt>
8 <dd>
9 <% if @user.url.present? %>
10 <%= link_to @user.url, @user.url %>
11 <% else %>
12 <span class="none">None given</span>
13 <% end %>
14 </dd>
15 <dt>Twitter:</dt>
16 <dd>
17 <% if @user.twitter_name.present? %>
18 <%= link_to @user.twitter_name, "http://twitter.com/#{@user.
19 twitter_name}" %>
20 <% else %>
21 <span class="none">None given</span>
22 <% end %>
23 </dd>
24 </dl>
25 </div>

47. 1 <div id="profile">
2 <dl>
3 <dt>Username:</dt>
4 <dd><%= @user.username %></dd>
5 <dt>Member Since:</dt>
6 <dd><%= @user.member_since %></dd>
7 <dt>Website:</dt>
8 <dd>
9 <% if @user.url.present? %>
10 <%= link_to @user.url, @user.url %>
11 <% else %>
12 <span class="none">None given</span>
13 <% end %>
14 </dd>
15 <dt>Twitter:</dt>
16 <dd>
17 <% if @user.twitter_name.present? %>
18 <%= link_to @user.twitter_name, "http://twitter.com/#{@user.
19 twitter_name}" %>
20 <% else %>
21 <span class="none">None given</span>
22 <% end %>
23 </dd>
24 </dl>
25 </div>

48. 1 class UserPresenter
2 attr_reader :user
3 delegate :username, :url, :twitter_name,
4 :full_name,:created_at to: :user
5
6 def initialize(user, template)
7 @user, @template = user, template
8 end
9
10 def member_since
11 user.created_at.strftime("%B %e, %Y")
12 end
13
14 def website
15 handle_none user.url { h.link_to(user.url, user.url) }
16 end
17
18 def twitter
19 handle_none user.twitter_name { h.link_to user.twitter_name, "http:
20 //twitter.com/#{user.twitter_name}" }
21 end
22
23 private
24 def h
25 @template
26 end
27
28 def handle_none(value)
29 ...
30 end
31 end

49. 1 class UserPresenter
2 attr_reader :user
3 delegate :username, :url, :twitter_name,
4 :full_name,:created_at to: :user
5
6 def initialize(user, template)
7 @user, @template = user, template
8 end
9
10 def member_since
11 user.created_at.strftime("%B %e, %Y")
12 end
13
14 def website
15 handle_none user.url { h.link_to(user.url, user.url) }
16 end
17
18 def twitter
19 handle_none user.twitter_name { h.link_to user.twitter_name, "http:
20 //twitter.com/#{user.twitter_name}" }
21 end
22
23 private
24 def h
25 @template
26 end
27
28 def handle_none(value)
29 ...
30 end
31 end

50. 1 class UserPresenter
2 attr_reader :user
3 delegate :username, :url, :twitter_name,
4 :full_name,:created_at to: :user
5
6 def initialize(user, template)
7 @user, @template = user, template
8 end
9
10 def member_since
11 user.created_at.strftime("%B %e, %Y")
12 end
13
14 def website
15 handle_none user.url { h.link_to(user.url, user.url) }
16 end
17
18 def twitter
19 handle_none user.twitter_name { h.link_to user.twitter_name, "http:
20 //twitter.com/#{user.twitter_name}" }
21 end
22
23 private
24 def h
25 @template
26 end
27
28 def handle_none(value)
29 ...
30 end
31 end

51. 1 class UserPresenter
2 attr_reader :user
3 delegate :username, :url, :twitter_name,
4 :full_name,:created_at to: :user
5
6 def initialize(user, template)
7 @user, @template = user, template
8 end
9
10 def member_since
11 user.created_at.strftime("%B %e, %Y")
12 end
13
14 def website
15 handle_none user.url { h.link_to(user.url, user.url) }
16 end
17
18 def twitter
19 handle_none user.twitter_name { h.link_to user.twitter_name, "http:
20 //twitter.com/#{user.twitter_name}" }
21 end
22
23 private
24 def h
25 @template
26 end
27
28 def handle_none(value)
29 ...
30 end
31 end

52. 1 <div id="profile">
2 <dl>
3 <dt>Username:</dt>
4 <dd><%= @user_presenter.username %></dd>
5 <dt>Member Since:</dt>
6 <dd><%= @user_presenter.member_since %></dd>
7 <dt>Website:</dt>
8 <dd><%= @user_presenter.website %></dd>
9 <dt>Twitter:</dt>
10 <dd><%= @user_presenter.twitter %></dd>
11 </dl>
12 </div>

53. 1 <div id="profile">
2 <dl>
3 <dt>Username:</dt>
4 <dd><%= @user_presenter.username %></dd>
5 <dt>Member Since:</dt>
6 <dd><%= @user_presenter.member_since %></dd>
7 <dt>Website:</dt>
8 <dd><%= @user_presenter.website %></dd>
9 <dt>Twitter:</dt>
10 <dd><%= @user_presenter.twitter %></dd>
11 </dl>
12 </div>

54. 1 def show
2 user = User.find(params[:id])
3 @user_presenter = UserPresenter.new(user, view_context)
4 end

55. 1 def show
2 user = User.find(params[:id])
3 @user_presenter = UserPresenter.new(user, view_context)
4 end

56. 1 class UserPresenter
2 attr_reader :user
3 delegate :username, :member_since, :url,
4 :twitter_name, :full_name,:created_at to: :user
5
6 def initialize(user, template)
7 @user, @template = user, template
8 end
9
10 def member_since
11 user.created_at.strftime("%B %e, %Y")
12 end
13
14 def website
15 handle_none user.url { h.link_to(user.url, user.url) }
16 end
17
18 def twitter
19 handle_none user.twitter_name { h.link_to user.twitter_name, "http:
20 //twitter.com/#{user.twitter_name}" }
21 end
22
23 private
24 def h
25 @template
26 end
27
28 def handle_none(value)
29 ...
30 end
31 end

57. gem 'draper'

58. 1 class UserPresenter < Draper::Decorator
2 delegate_all
3
4 def member_since
5 object.created_at.strftime("%B %e, %Y")
6 end
7
8 def website
9 handle_none object.url do
10 h.link_to(object.url, object.url)
11 end
12 end
13
14 def twitter
15 handle_none object.twitter_name do
16 h.link_to object.twitter_name,
17 "http://twitter.com/#{object.twitter_name}"
18 end
19 end
20
21 private
22 def handle_none(value)
23 ...
24 end
25 end

59. 1 class UserPresenter < Draper::Decorator
2 delegate_all
3
4 def member_since
5 object.created_at.strftime("%B %e, %Y")
6 end
7
8 def website
9 handle_none object.url do
10 h.link_to(object.url, object.url)
11 end
12 end
13
14 def twitter
15 handle_none object.twitter_name do
16 h.link_to object.twitter_name,
17 "http://twitter.com/#{object.twitter_name}"
18 end
19 end
20
21 private
22 def handle_none(value)
23 ...
24 end
25 end

60. 1 class UserPresenter < Draper::Decorator
2 delegate_all
3
4 def member_since
5 object.created_at.strftime("%B %e, %Y")
6 end
7
8 def website
9 handle_none object.url do
10 h.link_to(object.url, object.url)
11 end
12 end
13
14 def twitter
15 handle_none object.twitter_name do
16 h.link_to object.twitter_name,
17 "http://twitter.com/#{object.twitter_name}"
18 end
19 end
20
21 private
22 def handle_none(value)
23 ...
24 end
25 end

61. 1 class UserPresenter < Draper::Decorator
2 delegate_all
3
4 def member_since
5 object.created_at.strftime("%B %e, %Y")
6 end
7
8 def website
9 handle_none object.url do
10 h.link_to(object.url, object.url)
11 end
12 end
13
14 def twitter
15 handle_none object.twitter_name do
16 h.link_to object.twitter_name,
17 "http://twitter.com/#{object.twitter_name}"
18 end
19 end
20
21 private
22 def handle_none(value)
23 ...
24 end
25 end

62. 1 class UserPresenter < Draper::Decorator
2 delegate_all
3
4 def member_since
5 object.created_at.strftime("%B %e, %Y")
6 end
7
8 def website
9 handle_none object.url do
10 h.link_to(object.url, object.url)
11 end
12 end
13
14 def twitter
15 handle_none object.twitter_name do
16 h.link_to object.twitter_name,
17 "http://twitter.com/#{object.twitter_name}"
18 end
19 end
20
21 private
22 def handle_none(value)
23 ...
24 end
25 end

63. 1 class UserPresenter < Draper::Decorator
2 delegate_all
3
4 def member_since
5 object.created_at.strftime("%B %e, %Y")
6 end
7
8 def website
9 handle_none object.url do
10 h.link_to(object.url, object.url)
11 end
12 end
13
14 def twitter
15 handle_none object.twitter_name do
16 h.link_to object.twitter_name,
17 "http://twitter.com/#{object.twitter_name}"
18 end
19 end
20
21 private
22 def handle_none(value)
23 ...
24 end
25 end

64. 1 def show
2 @user = User.find(params[:id]).decorate
3 end

65. app/presenters

66. dhh says
helpers

67. Summary

68. References
• http://blog.codeclimate.com/blog/2012/10/17/7-
ways-to-decompose-fat-activerecord-models/
• https://gist.github.com/blaix/5764401
• https://blog.engineyard.com/2014/keeping-your-
rails-controllers-dry-with-services
• https://medium.com/@ryakh/rails-form-
objects-84b6849c886e

69. Railscasts
• http://railscasts.com/episodes/416-form-objects
• http://railscasts.com/episodes/398-service-
objects
• http://railscasts.com/episodes/287-presenters-
from-scratch
• http://railscasts.com/episodes/286-draper

70. Questions?
@krames