Un profondo punto di vista sul perché Ruby on Rails ha rivoluzionato lo sviluppo web. Questo talk focalizzerà la sua attenzione sul “Golden Path” di Rails, sui motivi del suo successo, sui problemi più comuni, e su come le sue API possano essere migliorate. Impareremo a trarre beneficio da uno strumento tanto potente quanto pericoloso, di come mitigare le implicazioni architetturali, di design e testabilità delle vostre applicazioni, migliorando la qualità del codice..

1. March 22nd, 2013
A Rails Criticism
how i learned to stop worrying about the Golden Path
Luca Guidi

2. AGENDA
intro

3. Luca Guidi
Senior Developer at Litmus
@jodosha - http//lucag uidi.com

4. litmus
Beautiful Email previews
Campaig n analytics
Spam filter tests
HTML code analysis
And many other..

5. Why Rails
has revolutionized web
development?
(IMHO)

6. Why Rails
has revolutionized web
development?
Convention Over
Config uration
(IMHO)
:)

7. Why Rails
has revolutionized web
development?
Dynamic and innovative
Convention Over
Config uration
ecosystem
(IMHO)
:)

8. Why Rails
has revolutionized web
development?
Dynamic and innovative
Convention Over
Productivity and
Developer uration
Config Happiness
ecosystem
(IMHO)
:)

9. ..but
The Framework is almost
ten years old

10. ..but
TheLot of Legacy Code
A Framework is almost
ten years old
is around

11. ..but
TheLot of Legacymajor
A Frameworkais Code
Upgrades to almost
release years old
ten are *painful*
is around

12. AGENDA
intro problems

13. Active
Record
Active
Record

14. Active
Record
Models != Records

15. Active
Record
Encapsulation violations
1 if article.statearticle.published?
1 unless != 'published'
2 article.update_attribute(state: 'published')
2 article.publish!
3 end 3 end
4 # not completely right...

16. Active
Record
Encapsulation violations
1 if article.statearticle.published?
1 unless != 'published'
2 article.update_attribute(state: 'published')
2 article.publish!
3 end 3 end
4 # not completely right...

17. Active
Record
Encapsulation violations
1 if article.statearticle.published?
1 unless != 'published'
2 article.update_attribute(state: 'published')
2 article.publish!
3 end 3 end
4 # not completely right...

18. Active
Record
Tell, Don’t Ask
1
2 violations
article.publish!
unless article.published?
# article.publish!
push the implementation
3 end
# into the model
4 # not completely right...

19. Active
Record
Tell, Don’t Ask
violations
1 article.publish!
unless article.published?
2 # article.publish!
push the implementation
3 end
# into the model
4 # not completely right...

20. Active
Record
Tell, Don’t Ask
violations
1 article.publish!
unless article.published?
2 # article.publish!
push the implementation
3 end
# into the model
4 # not completely right...

21. Active
Record
2
Implicit vs Explicit API
1 class Post < ActiveRecord::Base
1 Post.where(state:'published').
1 Post.most_recent_published
def self.most_recent_published(limit = 5)
3 2published.recent(limit).order('created_at DESC')
order('created_at DESC').
4 end
5 3 limit(5)
6 private
7 scope :published, ->() { where(state: 'published') }
8 scope :recent, ->(n) { limit(n) }
9 end

22. Active
Record
Implicit vs Explicit API
1 class Post < ActiveRecord::Base
2 1 Post.where(state:'published').
1 Post.most_recent_published
def self.most_recent_published(limit = 5)
3 2published.recent(limit).order('created_at DESC')
order('created_at DESC').
4 end
5 3 limit(5)
6 private
7 scope :published, ->() { where(state: 'published') }
8 scope :recent, ->(n) { limit(n) }
9 end

23. Active
Record
Implicit vs Explicit API
1 class Post < ActiveRecord::Base
2 1 Post.where(state:'published').
1 Post.most_recent_published
def self.most_recent_published(limit = 5)
3 2published.recent(limit).order('created_at DESC')
order('created_at DESC').
4 end
5 3 limit(5)
6 private
7 scope :published, ->() { where(state: 'published') }
8 scope :recent, ->(n) { limit(n) }
9 end

24. Active
Record
Implicit vs Explicit API
1 class Post < ActiveRecord::Base
2 1 Post.where(state:'published').
1 Post.most_recent_published
def self.most_recent_published(limit = 5)
3 2published.recent(limit).order('created_at DESC')
order('created_at DESC').
4 end
5 3 limit(5)
6 private
7 scope :published, ->() { where(state: 'published') }
8 scope :recent, ->(n) { limit(n) }
9 end

25. Active
Record
Callbacks abuse
Non-persistence logic is
tight to the persistence
life cycle.
Eg. Sending emails

26. Active
Record
Testability issues
Micheal Feathers

27. Active
Record
A test is not a unit test if it talks
Testability issues
to a database.
Micheal Feathers

28. Action
Controller
Action
Controller
It doesn’t affect too much your
architecture, but it has strange
OOP design.

29. Action
Controller
1 class PostsController < ApplicationController
2 before_filter :authenticate
Frankenstein Controllers
3
4 def new
5 end
6
7 def create
8 @post = Post.new(params[:post])
9
10 if @post.save
11 redirect_to post_url(@post), notice: 'Yay!'
12 else
13 render :new
14 end
15 end
16 end

30. Action
Controller
Frankenstein Controllers
1 class PostsController < ApplicationController
2 before_filter :authenticate
3
4 def new
5 end
6
7 def create
8 @post = Post.new(params[:post])
9
10 if @post.save
11 redirect_to post_url(@post), notice: 'Yay!'
12 else
13 render :new
14 end
15 end
16 end

31. Action
Controller
Frankenstein Controllers
1 class PostsController < ApplicationController
2 before_filter :authenticate
3
4 def new
5 end
6
7 def create
8 @post = Post.new(params[:post])
9
10 if @post.save
11 redirect_to post_url(@post), notice: 'Yay!'
12 else
13 render :new
14 end
15 end
16 end

32. Action
Controller
Frankenstein Controllers
1 class PostsController < ApplicationController
2 before_filter :authenticate
3
4 def new
5 end
6
7 def create
8 @post = Post.new(params[:post])
9
10 if @post.save
11 redirect_to post_url(@post), notice: 'Yay!'
12 else
13 render :new
14 end
15 end
16 end

33. Action
Controller
Frankenstein Controllers
1 class PostsController < ApplicationController
2 before_filter :authenticate
3
4 def new
5 end
6
7 def create
8 @post = Post.new(params[:post])
9
10 if @post.save
11 redirect_to post_url(@post), notice: 'Yay!'
12 else
13 render :new
14 end
15 end
16 end

34. Action
Controller
Frankenstein Controllers
1 class PostsController < ApplicationController
2 before_filter :authenticate
3
4 def new
5 end
6
7 def create
8 @post = Post.new(params[:post])
9
10 if @post.save
11 redirect_to post_url(@post), notice: 'Yay!'
12 else
13 render :new
14 end
15 end
16 end

35. Action
Controller
1 class PostsController < ApplicationController
2 # ...
Odd classes
3
4 def create
5 @post = Post.new(params[:post])
6
7 if @post.save
8 # ...
9 else
10 # ...
11 end
12 end
13 end

36. Action
Controller
Odd classes
1 class PostsController < ApplicationController
2 # ...
3
4 def create
5 @post = Post.new(params[:post])
6
7 if @post.save
8 # ...
9 else
10 # ...
11 end
12 end
13 end

37. Action
Controller
Odd classes
1 class PostsController < ApplicationController
2 # ...
3
4 def create
5 @post = Post.new(params[:post])
6
7 if @post.save
8 # ...
9 else
10 # ...
11 end
12 end
13 end

38. Action
Controller
Odd classes
1 class PostsController < ApplicationController
2 # ...
3
4 def create
5 @post = Post.new(params[:post])
6
7 if @post.save
8 # ...
9 else
10 # ...
11 end
12 end
13 end

39. Action
Controller
3
4
Encapsulation violations
1 class PostsController < ApplicationController
2 # ...
def create
5 @post = Post.new(params[:post])
6 # ...
7 end
8 end

40. Action
Controller
Encapsulation violations
1 class PostsController < ApplicationController
2 # ...
3
4 def create
5 @post = Post.new(params[:post])
6 # ...
7 end
8 end

41. Action
Controller
1 describe PostsController do
Testability issues
2 it 'assigns @posts' do
3 Post.should_receive(:most_recent_published).
4 and_return(posts = [mock])
5 get :index
6
7 expect(assigns(:posts)).to eq(posts)
8 end
9 end

42. Action
Controller
Testability issues
1 describe PostsController do
2 it 'assigns @posts' do
3 Post.should_receive(:most_recent_published).
4 and_return(posts = [mock])
5 get :index
6
7 expect(assigns(:posts)).to eq(posts)
8 end
9 end

43. Action
Controller
Testability issues
1 describe PostsController do
2 it 'assigns @posts' do
3 Post.should_receive(:most_recent_published).
4 and_return(posts = [mock])
5 get :index
6
7 expect(assigns(:posts)).to eq(posts)
8 end
9 end

44. Action
Controller
Testability issues
1 describe PostsController do
2 it 'assigns @posts' do
3 Post.should_receive(:most_recent_published).
4 and_return(posts = [mock])
5 get :index
6
7 expect(assigns(:posts)).to eq(posts)
8 end
9 end

45. Action
Controller
Testability issues
1 describe PostsController do
2 it 'assigns @posts' do
3 Post.should_receive(:most_recent_published).
4 and_return(posts = [mock])
5 get :index
6
7 expect(assigns(:posts)).to eq(posts)
8 end
9 end

46. Action
Controller
Testability issues
1 describe PostsController do
2 it 'assigns @posts' do
3 Post.should_receive(:most_recent_published).
4 and_return(posts = [mock])
5 get :index
6
7 expect(assigns(:posts)).to eq(posts)
8 end
9 end

47. Action
View
Action
View

48. Action
View
Views aren’t views
(but templates with logic)
Without “real” views (or In an ideal world we
presenters), we’re tempted to shouldn’t test our
push presentational methods templates.
into the models.

49. Action
View
Helpers are
functional programming
1 def user_full_name(user)
2 [ user.first_name, user.last_name ].join(' ')
3 end
4
5 url_for
6 # vs Half-assed way to solve
7 Url.for presentational problems in
8 ActionView.
9 posts_url

50. Action
View
Helpers are
functional programming
1 def user_full_name(user)
2 [ user.first_name, user.last_name ].join(' ')
3 end
4
5 url_for
6 # vs Half-assed way to solve
7 Url.for presentational problems in
8 ActionView.
9 posts_url

51. Ruby on
Rails
Ruby on
Rails

52. Ruby on
Rails
Rails isn’t a framework,
but an application
template

53. Ruby on
Rails
Rails is multi-paradig m
as Ruby is.

54. AGENDA
intro problems solutions

55. Solutions
Decouple your logic from
ActiveRecord as much as
possible.
AR is focused on data, but
OOP is about behavior.

56. Solutions
Don’t think in
ActiveRecord terms.
Database is a detail,
forget about associations,
scopes, validations..

57. Solutions
Let your public API
to declare intents.
Let your design to emerge
via TDD.

58. Solutions
Keep methods and
accessors private as
much as possible.
Public APIs are hard to
maintain as the codebase
and the team grows.

59. Solutions
Skinny controllers
and
skinny models.
Use ser vice objects or DCI, they
are easier and faster to test.

60. Solutions
Don’t be afraid to extract
ad-hoc classes for
specific responsibilities.
Inner classes are your friends,
they help you with details, and
aren’t part of your public API.

61. Solutions
Use DIY presenters
They will help you to keep your
models clean from presentational
logic.

62. Solutions
Refactor, refactor,
refactor.

63. AGENDA
intro problems solutions conclusion

64. Q&A

65. me@lucag uidi.com
@jodosha
https://speakerdeck.com/jodosha/a-rails-criticism
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