DCI And Rails (Jakarta.rb February 2014)

My presentation during Jakarta.rb meetup on February 2014 about "DCI and Rails"

Transcript

1. Hi, my name is Giovanni Jakarta.rb February 2014
2. I Work for…
4. Thanks!!
5. I’m having problem with remembering people faces and names ! self-diagnosed with mild OCD ! 70% of my time during work is spent on reviewing codes from collaborators 6JKUKUOG
6. My Main Concern Ensure that codes is as comprehendible as possible, make sure that any people whom participate in the project can understand and contribute effortlessly even though the project grows larger and larger and larger ! RGTHQTOCPEGOC[GXGPDGCUGEQPFEKVK\GPKPUQOGECUG
8. Today
9. DCI (a.k.a Data Context Interaction) by Trygve Reenskaug KPECUG[QWFQPņVMPQYVJKUCYGUQOGOCPJGņU CNUQVJGQPGYJQOKPXGPVGF/8%DVY
10. I’m (currently) not a DCI proponent ! I’m (still) not using it for production (only experimenting with it) ! I understand that Rails still can’t support it 100% yet
11. $WVOCP +ņOKPVTKIWGF
12. Common Rails developer evolution on “where to put my logic?” ! QTKPUGTVCP[QVJGTYGD/8%HTCOGYQTMU .GVņUVCMGCNQQMCV
13. Put logic everywhere.. in views in controllers etc… #TG[QWUWTGKVņUPQVLWUV[QW)KQ!
14. <% people = Person.where("added_at > ? AND deleted = ?", Time.now.utc, false).order("last_name, first_name") %> <% people.reject { |p| p.address.nil? }.each do |person| %> <div id="person-<%= person.new_record? ? "new" : person.id %>"> <span class="name"> <%= person.last_name %>, <%= person.first_name %> </span> <span class="age"> <%= (Date.today - person.birthdate) / 365 %> </span> </div> <% end %>
15. Keep logic out from views DWVUVKNNRWVCNQVQH NQIKEKPEQPVTQNNGTU
16. <% @people.each do |person| %> <div id="person-<%= person.new_record? ? "new" : person.id %>"> <span class="name"> <%= person.last_name %>, <%= person.first_name %> </span> <span class="age"> <%= (Date.today - person.birthdate) / 365 %> </span> </div> <% end %> class PeopleController < ActionController::Base def index @people = Person.where("added_at > ? AND deleted = ?", Time.now.utc, false).order("last_name, first_name") @people = @people.reject { |p| p.address.nil? } end end
17. “Fat model, skinny controller” *GTGKUVJGOCPVTCVJCVYG MPQYCPFNQXG
18. class Person < ActiveRecord::Base def self.find_recent people = Person.where("added_at > ? AND deleted = ?", Time.now.utc, false).order("last_name, first_name") people = people.reject { |p| p.address.nil? } end ! def name "#{last_name}, #{first_name}" end ! def age (Date.today - person.birthdate) / 365 end ! def pseudo_id new_record? ? "new" : id end end
19. <% @people.each do |person| %> <div id="person-<%= person.pseudo_id %>"> <span class="name"><%= person.name %></span> <span class="age"><%= person.age %></span> </div> <% end %> class PeopleController < ActionController::Base def index @people = Person.find_recent end end
20. But, was anything fat ever good in our app codebase? ! +UVKNNFQPņVMPQYVJGCPUYGTHQTVJKU
21. Class  User  <<  ActiveRecord::Base   !   def  process1_method1     …     end   !   def  process1_method2     …     end   ! end
22. Class  User  <<  ActiveRecord::Base   !   def  process1_method1     …     end   !   def  process1_method2     …     end   !   def  process2_method1     …     end   !   def  process2_method2     …     end   ! end
23. Class  User  <<  ActiveRecord::Base   !   def  process1_method1     …     end   !   def  process1_method2     …     end   !   def  process2_method1     …     end   !   def  process2_method2     …     end   !   def  process1_method3     …     end   !   def  process1_method4     …     end   !   def  process3_method1     …     end   !   def  process3_method2     …     end   ! end
24. Class  User  <<  ActiveRecord::Base   !   def  process1_method1     …     end   !   def  process1_method2     …     end   !   def  process2_method1     …     end   !   def  process2_method2     …     end   !   def  process1_method3     …     end   !   def  process1_method4     …     end   !   def  process3_method1     …     end   !   def  process3_method2     …     end   !   def  process1_method1     …     end   !   def  process1_method2     …     end   !   def  process2_method1     …     end   !   def  process2_method2     …     end   !   def  process1_method3     …     end   !   def  process1_method4     …     end   !   def  process3_method1     …     end   !   def  process3_method2     …     end   !   def  process1_method1     …     end   !   def  process1_method2     …     end   !   def  process2_method1     …     end   !   def  process2_method2     …     end   !   def  process1_method3     …     end   !   def  process1_method4     …     end   !   def  process3_method1     …     end   !   def  process3_method2     …     end   ! end
25. Difficult to comprehend due to too much information in model…
26. ActiveSupport::Concern  !!!
27. Class  User  <<  ActiveRecord::Base     include  Commentable     include  Taggable     include  Manageable     include  ShoppingCartable     include  BlahBlah     …etc   end
28. 9JCVņUYTQPIYKVJVJKU! Class  User  <<  ActiveRecord::Base     include  Commentable     include  Taggable     include  Manageable     include  ShoppingCartable     include  BlahBlah     …etc   end
29. Developer still have to makes sense what goes where ! Business Process cannot be evaluated procedurally
30. Wait.. ! If we use BDD we can see and build business processes using the integration test, right?
31. Wait.. ! If we use BDD we can see and build business processes using the integration test, right? 6JCVKU%QTTGEV
32. We can actually stop here. +H[QWFQňHCVOQFGNUUMKPP[EQPVTQNNGTUʼnWUGCEVKXGUWRRQTVEQPEGTP CPFRTCEVKEG$&&VJGPEQPITCVWNCVKQPU[QWņTGNKXKPIQPVJGGFIG
33. But what’s DCI actually all about then?
34. DCI is about assigning roles to a model in a context /[WPFGTUVCPFKPIQH&%+ EQPVGZV#-#WUGTUVQT[
35. A model must not have any business process related methods.. ! business process and model must be tightly separated..
36. Wait Whaaaaaat ?..
37. Class  User  <<  ActiveRecord::Base     include  Commentable     include  Taggable     include  Manageable     include  ShoppingCartable     include  BlahBlah     …etc   end ;GCJVJKUKUYTQPIKP&%+
38. So where should we put our code then? ! not in views.. not in controllers.. not in models.. not in concerns..
39. We’ll have new kind of codes: Roles and Contexts
40. class User < ActiveRecord::Base validates :name, :presence => true end ! class Book < ActiveRecord::Base validates :title, :presence => true end 6JKUKUQWTOQFGNU
41. module Customer def add_to_cart(book) self.cart << book end end 6JKUKUQWTTQNG
42. 6JKUKUQWTEQPVGZV class AddToCartContext attr_reader :user, :book ! def self.call(user, book) AddToCartContext.new(user, book).call end ! def initialize(user, book) @user, @book = user, book @user.extend Customer end ! def call @user.add_to_cart(@book) end end
43. class BookController < ApplicationController def add_to_cart AddToCartContext.call(current_user, Book.find(params[:id])) end end 6JKUKUQWTEQPVTQNNGT
44. That my friends, was DCI…
45. Something not right..
46. class AddToCartContext attr_reader :user, :book ! def self.call(user, book) AddToCartContext.new(user, book).call end ! def initialize(user, book) @user, @book = user, book @user.extend Customer end ! def call @user.add_to_cart(@book) end end
47. class AddToCartContext attr_reader :user, :book ! def self.call(user, book) AddToCartContext.new(user, book).call end ! def initialize(user, book) @user, @book = user, book @user.extend Customer end ! def call @user.add_to_cart(@book) end end 2GTHQTOCPEGRTQDNGOJGTG
48. What I showed you was not an official method to do DCI in Rails. ! In fact, no official method exist yet.
49. DHH is against DCI? 9JCV4CKNU%TGCVQTUCKFŎ
51. “This approach to breaking up domain logic into concerns is similar in some ways to the DCI notion of Roles. It doesn’t have the run-time mixin acrobatics nor does it have the “thy models shall be completely devoid of logic themselves” prescription, but other than that, it’ll often result in similar logic extracted using similar names.”
52. But..
53. Imagine a time when business process related code can be placed exactly within the actual code (not the test). ! And tightly separated from the model. 9GNN+ņOIQPPCNQUGO[LQDDGECWUGO[ENKGPVUECPEQFG EQORNKECVGFDWUKPGUURTQEGUUD[VJGOUGNXGUKHVJCVJCRRGPU
54. Conclusion
55. Ruby and Rails still have long ways to go to support DCI completely ! But you can still use it now if you want to.. (QQFHQTVJQWIJVU
56. Some says SCALA is well-suited for DCI (QQFHQTVJQWIJVU
57. http://signalvnoise.com/posts/3372-put-chubby-models-on- a-diet-with-concerns ! http://www.sitepoint.com/dci-the-evolution-of-the-object- oriented-paradigm/ ! http://mikepackdev.com/blog_posts/24-the-right-way-to- code-dci-in-ruby ! http://dec0de.me/2013/02/dci-performance/ ! “Clean Ruby v0.9” - Jim Gay 4GHGTGPEGU
58. Thanks!! Okay, that’s all lads..
59. Question? @giosakti - mightygio.com - starqle.com