Beyond the Rails Way 

2 Patricia Luz Bastos 

3 Architecture 

4 

5 

6 

7 Not so good 

8 class UserGroupsController def create # Assume @group is loaded from a before_action method if !current_user.is_old_enough_to_join_group?(@group) flash[:alert] = I18n.t('admin.trestle.flash.too_young') elsif current_user.is_group_limit_reached? flash[:alert] = I18n.t('admin.trestle.flash.too_many_groups') else user_group = UserGroup.new(user_id: current_user.id, group_id: @group.id) if user_group.save flash[:notice] = I18n.t('admin.trestle.flash.successfully_joined_group') else flash[:alert] = I18n.t('admin.trestle.flash.could_not_join_group') end end redirect_to group_path(@group) end end 

9 class User < ApplicationRecord MAX_NUMBER_OF_GROUPS = 10 has_many :user_groups has_many :groups, through: :user_groups def is_old_enough_to_join_group?(group) age > group.minimum_age end def is_group_limit_reached? groups.count >= MAX_NUMBER_OF_GROUPS end end 

© 2017 InspiraSign - Template All rights reserved 10 “But what if there was a way to have both skinny models AND skinny controllers?!” 

11 Robert Martin Clean Code 

12 Independent of Frameworks 

13 Testable 

14 Independent of UI 

15 Independent of Database 

16 Independent of any external agency 

17 https://8thlight.com/blog/uncle-bob/2012/08/13/the-clean-architecture.html 

18 Use Cases 

19 CreateUser Name Format Name Minimum 2 characters maximum 50 characters. Email Must have valid format as in the example: [email protected]. Password At least 6 characters, maximum 15 characters. Password Confirmation Must be filled in identically to the password. Main Flow - Set of steps Exception Flow - What happened when things do not go well 

20 Interactor 

21 Interactors Entity Entity Business rules 

22 Rails architecture by Uncle Bob 

23 Code Samples 

24 Example 1 

25 Boundary 

26 UseCase 

27 Example 2 

28 

29 

30 

31 

32 Tell-don’t-ask 

33 

34 

35 Example 3 

36 

37 Other examples 

38 TrailBlazer 

39 

40 

41 RetroMocha/Obvious 

42 

43 

44 

45 

46 Gem Interactor 

47 

48 

49 

50 

51 Better 

52 class UserGroupsController def create result = AddUserToGroup.call group: @group, user: current_user message = result.message if result.success? flash[:notice] = message else flash[:alert] = message end redirect_to group_path(@group) end end 

53 class AddUserToGroup include Interactor def call fail! message: I18n.t('admin.trestle.flash.too_young') unless is_old_enough_to_join_group? fail! message: I18n.t('admin.trestle.flash.too_many_groups') unless group_limit_reached? if create_new_user_group context[:message] = I18n.t('admin.trestle.flash.successfully_joined_group') else fail! message: I18n.t('admin.trestle.flash.could_not_join_group') end end private def group_limit_reached? context[:user].groups.count >= User::MAX_NUMBER_OF_GROUPS end def is_old_enough_to_join_group? context[:user].age >= context[:group].minimum_age end def create_new_user_group context[:user_group] = UserGroup.new(user_id: context[:user].id, group_id: context[:group].id) context[:user_group].save end end 

result = AddUserToGroup.call group: @group, user: current_user puts result.user_group => # puts result.message => You have successfully joined the Example group! 

55 “But… More Lines of Code?!” 

“Many Ruby/Rails developers married to Rails " 56 

57 Thank you! @patricialuzbast
 patybastos