Patterns to deal with big ActiveRecord models

“Skinny controllers, fat models” is a well-known practice in the Rails community that everyone seems to follow. However, as your application evolves and your models grow, maintaining them can become less enjoyable than it used to be.

In the last few years, the community has been proposing patterns and techniques to deal with big AR models. Presenters, Service objects, Concerns or DCI are only a few examples of solutions suggested to alleviate the pain caused by gigantic models.

In this talk, we will critically explore these patterns in their different flavours. We'll compare them in order to expose their strengths and weaknesses and you'll learn when and how to use them to keep your Rails models as pleasurable to deal with as the first day.

Transcript

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4. require_dependency,'topic_view' require_dependency,'rate_limiter' require_dependency,'text_sentinel' require_dependency,'text_cleaner' class,Topic,<,ActiveRecord::Base ,,include,ActionView::Helpers ,,include,RateLimiter::OnCreateRecord ,,def,self.max_sort_order ,,,,2**31,7,1 https://github.com/discourse/discourse/blob/master/app/models/topic.rb
5. require_dependency,'slug' require_dependency,'avatar_lookup' require_dependency,'topic_view' require_dependency,'rate_limiter' require_dependency,'text_sentinel' require_dependency,'text_cleaner' class,Topic,<,ActiveRecord::Base ,,include,ActionView::Helpers ,,include,RateLimiter::OnCreateRecord ,,def,self.max_sort_order ,,,,2**31,7,1 ,,end ,,def,self.featured_users_count ,,,,4 ,,end ,,versioned,if:,:new_version_required? ,,acts_as_paranoid ,,after_recover,:update_flagged_posts_count ,,after_destroy,:update_flagged_posts_count ,,rate_limit,:default_rate_limiter https://github.com/discourse/discourse/blob/master/app/models/topic.rb
6. https://github.com/discourse/discourse/blob/master/app/models/topic.rb 
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16. !!class!Article!<!ActiveRecord::Base !!!!attr_accessor!:moderation_option ! !!!!attr_accessible!:text,!:reply_to_i ! !!!!belongs_to!:topic !!!!belongs_to!:user,!!!!!:class_name! !!!!belongs_to!:reply_to,!:class_name!
17. !!!belongs_to!:user,!!!!!:class_name!=>!Fore !!!belongs_to!:reply_to,!:class_name!=>!"Pos !!!has_many!:replies,!:class_name!!=>!"Post" !!!!!!!!!!!!!!!!!!!!!!:foreign_key!=>!"reply !!!!!!!!!!!!!!!!!!!!!!:dependent!!!=>!:nulli !!! !!!has_many!:taggings !!!has_many!:tags,!:through!=>!:taggings !!!validates!:text,!:presence!=>!true !!!delegate!:forum,!:to!=>!:topic !!!after_create!:set_topic_last_post_at !!!after_create!:skip_pending_review
18. !!!!end !!!!def!pending_review !!!!!!where!:state!=>!'pending_review' !!!!end !!!!def!spam !!!!!!where!:state!=>!'spam' !!!!end !!!! !!!!def!tagged_with(tag) !!!!!!joins(:taggings!=>!:tags).where(:tags!=>!{!:name!=>!tag!}) !!!!end !!!!def!visible !!!!!!joins(:topic).where(:forem_topics!=>!{!:hidden!=>!false!}) !!!!end !!end !! !!def!tag_names=(tag_list) !!!!assign_tag_list!tag_list !!end !!private
19. !!!!!end !!!end !!! !!!def!tag_names=(tag_list) !!!!!assign_tag_list!tag_list !!!end !!!private !!!def!subscribe_replier !!!!!if!topic!&&!user
20. ! !!!!def!blacklist_user !!!!!!user.update_attribute(:forem_state,!"spam")!if!user !!!!end !!!! !!!!def!assign_tag_list(tag_list) !!!!!!tag_names!=!tag_list.gsub(/\s+/,!"").split(",") !!!!!!existing!=!self.tags.map!{|t|!t.name!} !!!!!!(existing!@!tag_names).each!do!|name| !!!!!!!!self.tags.delete!Tag.find_by_name(name) !!!!!!end !!!!!!tag_names.each!do!|name| !!!!!!!!self.tags!<<!Tag.find_or_create_by_name(name) !!!!!!end! !!!!end !!end
21. !!class!Article!<!ActiveRecord::Base !!!!attr_accessor!:moderation_option ! !!!!attr_accessible!:text,!:reply_to_id,!:tag_names ! !!!!belongs_to!:topic !!!!belongs_to!:user,!!!!!:class_name!=>!Forem.user_class.to_s !!!!belongs_to!:reply_to,!:class_name!=>!"Post" ! !!!!has_many!:replies,!:class_name!!=>!"Post", !!!!!!!!!!!!!!!!!!!!!!!:foreign_key!=>!"reply_to_id", !!!!!!!!!!!!!!!!!!!!!!!:dependent!!!=>!:nullify !!!! !!!!has_many!:taggings !!!!has_many!:tags,!:through!=>!:taggings ! !!!!validates!:text,!:presence!=>!true ! !!!!delegate!:forum,!:to!=>!:topic ! !!!!after_create!:set_topic_last_post_at !!!!after_create!:skip_pending_review !!!!after_save!:email_topic_subscribers ! !!!!class!<<!self !!!!!!def!by_created_at !!!!!!!!order!:created_at !!!!!!end ! !!!!!!def!pending_review !!!!!!!!where!:state!=>!'pending_review' !!!!!!end ! !!!!!!def!spam !!!!!!!!where!:state!=>!'spam' !!!!!!end !!!!!! !!!!!!def!tagged_with(tag) !!!!!!!!joins(:taggings!=>!:tags).where(:tags!=>!{!:name!=>!tag!}) !!!!!!end ! !!!!!!def!visible !!!!!!!!joins(:topic).where(:forem_topics!=>!{!:hidden!=>!false!}) !!!!!!end !!!!end !!!! !!!!def!tag_names=(tag_list) !!!!!!assign_tag_list!tag_list !!!!end ! !!!!private ! !!!!def!subscribe_replier !!!!!!if!topic!&&!user !!!!!!!!topic.subscribe_user(user.id) !!!!!!end !!!!end ! !!!!def!set_topic_last_post_at !!!!!!topic.update_attribute(:last_post_at,!created_at) !!!!end ! !!!!def!blacklist_user !!!!!!user.update_attribute(:forem_state,!"spam")!if!user !!!!end !!!! !!!!def!assign_tag_list(tag_list) !!!!!!tag_names!=!tag_list.gsub(/\s+/,!"").split(",") !!!!!!existing!=!self.tags.map!{|t|!t.name!} !!!!!!(existing!@!tag_names).each!do!|name| !!!!!!!!self.tags.delete!Tag.find_by_name(name) !!!!!!end !!!!!!tag_names.each!do!|name| !!!!!!!!self.tags!<<!Tag.find_or_create_by_name(name) !!!!!!end! !!!!end !!end
22. before_validation after_validation before_save before_create after_create after_save after_commit
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29. create_table)"schedulings")do)|t| ))#"... ))t.integer))"workflow_offset" ))t.string)))"workflow_asset_url" ))t.text)))))"workflow_details" ))t.boolean))"workflow_sent" ))t.string)))"workflow_web_url" ))t.string)))"workflow_template_url"
30. class)Scheduling)<)ActiveRecord::Base ))#"... ))include)Workflow
31. class)SchedulingsController)<)ApplicationController class)WorkflowsController)<)ApplicationController
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34. class)Workflow)<)ActiveRecord::Base ))belongs_to):scheduling
35. class)Scheduling)<)ActiveRecord::Base ))#"... ))has_one):workflow
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39. ActiveModel
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42. class!Signup !!extend!ActiveModel::Naming !!include!ActiveModel::Conversion !!include!ActiveModel::Validations !!attr_accessor!:name !!attr_accessor!:company_name !!attr_accessor!:email !!validates!:email,!presence:!true !!#"…"more"validations"… !!#"Virtual"models"are"never"themselves"persisted !!def!persisted? !!!!false !!end !!def!save !!!!if!valid? !!!!!!persist! !!!!!!true !!!!else !!!!!!false !!!!end !!end private !!def!persist! !!!!@company!=!Company.create!(name:!company_name) !!!!@user!=!@company.users.create!(name:!name,!email:!email) !!end end class!SignupsController!<!ApplicationController !!def!create http://blog.codeclimate.com/blog/2012/10/17/7-ways-to-decompose-fat-activerecord-models/
43. class)SignupsController)<)ApplicationController ))def)create ))))@signup)=)Signup.new(params[:signup]) ))))if)@signup.save ))))))redirect_to)dashboard_path ))))else ))))))render)"new" ))))end ))end end http://blog.codeclimate.com/blog/2012/10/17/7-ways-to-decompose-fat-activerecord-models/
44. class)SimpleModel ))extend)ActiveModel::Naming ))include)ActiveModel::Conversion ))include)ActiveModel::Validations ))#"Virtual"models"are"never"themselves"persisted ))def)persisted? ))))false ))end ))def)save ))))if)valid? ))))))persist! ))))))true ))))else ))))))false ))))end ))end end
45. class)Signup)<)SimpleModel ))attr_accessor):name, ))HHHHHHHHHHHHHH:company_name, ))HHHHHHHHHHHHHH:email ))validates):email,)presence:)true ))#"…"more"validations"… ))def)persist! ))))@company)=)Company.create!(name:)company_name) ))))@user)=)@company.users.create!(name:)name,)email:)email) ))end end
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47. module)DogFort ))def)call_dog ))))puts)"this)is)dog!" ))end end class)Dog ))include)DogFort end http://schneems.com/post/21380060358/concerned-about-code-reuse
48. ActiveSupport::Concern
49. module)M ))extend)ActiveSupport::Concern )))) ))included)do ))))scope):disabled,)where(:disabled)=>)true) ))end )) ))module)ClassMethods ))))#"class"methods ))end ))#"instance"methods end http://api.rubyonrails.org/classes/ActiveSupport/Concern.html
50. class)Article)<)ActiveRecord::Base ))include)Taggable
51. module!Taggable !!extend!ActiveSupport::Concern !!included!do !!!!has_many!:taggings !!!!has_many!:tags,!through:!:taggings !!!!scope!:tagged_with,!+>(tag_name)!do !!!!!!joins(:tags).where(tags:!{!name:!tag_name!})! !!!!end !!end !!def!tag_list !!!!tags.pluck(:name).join(',!') !!end !!def!tag_list=(tag_list) !!!!assign_tag_list!tag_list !!end !!private !!def!assign_tag_list(tag_list) !!!!tag_names!=!tag_list.split(',').map(&:strip).uniq !!!!self.tags!=!tag_names.map!do!|tag_name|! !!!!!!Tag.where(name:!tag_name).first_or_initialize !!!!end !!end end
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56. app/controllers/concerns app/models/concerns
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60. #"app/models/article.rb class)Article)<)ActiveRecord::Base ))include)Accessors ))include)Validations ))include)Associations ))include)Scopes ))#"... end
61. #"app/models/article.rb class)Article)<)ActiveRecord::Base ))include)Taggable ))include)Searchable ))include)Movable ))include)Visible ))include)Trashable ))#"... end
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63. http://blog.codeclimate.com/blog/2012/10/17/7-ways-to-decompose-fat-activerecord-models/ class)UserAuthenticator ))def)initialize(user) ))))@user)=)user ))end ))def)authenticate(unencrypted_password) ))))return)false)unless)@user ))))if)BCrypt::Password.new(@user.password_digest))==)unencrypted_password ))))))@user ))))else ))))))false ))))end ))end end
64. user)=)User.where(email:)params[:email]).first UserAuthenticator.new(user).authenticate(params[:password])
65. user)=)User.where(email:)params[:email]).first UserAuthenticator.new(user).authenticate(params[:password])
66. https://gist.github.com/brynary/4670393 user!=!User.where(email:!params[:email]).first UserAuthenticator.new(user).authenticate(params[:password]) class!ActiveUserPolicy !!LOGIN_PERIOD!=!14.days !! !!def!initialize(user) !!!!@user!=!user !!end !!def!active? !!!!@user.email_confirmed?!&& !!!!@user.last_login_at!<!LOGIN_PERIOD.ago !!end !!class!Query !!!!def!initialize(relation!=!User.scoped) !!!!!!@relation!=!relation !!!!end !!!!def!find_each(&block) !!!!!!@relation. !!!!!!!!where(email_confirmed:!true). !!!!!!!!where('last_login!<!?',!LOGIN_PERIOD.ago). !!!!!!!!find_each(&block) !!!!end !!end end ActiveUserPolicy.active?(user)
67. ActiveUserPolicy.new(user).active? ActiveUserPolicy::Query.new(current_company.users).find_each)do)|user| ))#"... end
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69. module)User::Active ))extend)ActiveSupport::Concern ))included)do ))))scope):active,)M>)do ))))))where(email_confirmed:)true). ))))))where('last_login)<)?',)14.days.ago) ))))end ))end ))def)active? ))))user.email_confirmed?)&& ))))user.last_login_at)<)14.days.ago ))end end https://gist.github.com/cavalle/4660239
70. https://gist.github.com/brynary/4670393 user!=!User.where(email:!params[:email]).first UserAuthenticator.new(user).authenticate(params[:password]) class!ActiveUserPolicy !!LOGIN_PERIOD!=!14.days !! !!def!initialize(user) !!!!@user!=!user !!end !!def!active? !!!!@user.email_confirmed?!&& !!!!@user.last_login_at!<!LOGIN_PERIOD.ago !!end !!class!Query !!!!def!initialize(relation!=!User.scoped) !!!!!!@relation!=!relation !!!!end !!!!def!find_each(&block) !!!!!!@relation. !!!!!!!!where(email_confirmed:!true). !!!!!!!!where('last_login!<!?',!LOGIN_PERIOD.ago). !!!!!!!!find_each(&block) !!!!end !!end end ActiveUserPolicy.active?(user)
71. user.active? current_company.users.active.each)do)|user| ))#"... end
72. ActiveUserPolicy.active?(user) ActiveUserPolicy::Query.new(current_company.users).find_each)do)|user| ))#"... end
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74. class)Commenter ))def)initialize(person) ))))@person)=)person ))end ))def)recent_comments ))))@person.comments.where("created_at)>)?",)3.days.ago) ))end ))def)post_comment(text) ))))@person.comments.create(:body)=>)text) ))end ))def)update_comment(new_text) ))))raise)"Comment)not)owned)by)this)person")unless)comment.author)==)@person ))))comment.update_attribute(:body,)new_text) ))end end https://gist.github.com/4341122
75. class)Commenter ))def)initialize(person) ))))@person)=)person ))end ))def)recent_comments ))))@person.comments.where("created_at)>)?",)3.days.ago) ))end ))def)post_comment(text) ))))@person.comments.create(:body)=>)text) ))end ))def)update_comment(new_text) ))))raise)"Comment)not)owned)by)this)person")unless)comment.author)==)@person ))))comment.update_attribute(:body,)new_text) ))end end https://gist.github.com/4341122
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78. http_client)=)HTTPClient.new('https://api.github.com') github)=)Github::Client.new(http_client) github.get_user(params[:name])
79. TwitterPoster.new(current_user,)@comment.body).post FacebookPoster.new(current_user,)@comment.body).post NotificationsMailer.new_comment(@comment).deliver
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83. http://weblog.jamisbuck.org/2006/10/18/skinny-controller-fat-model
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85. class)CommentsController)<)ApplicationController ))#... ))def)create ))))@comment)=)@post.comments.build(post_params) ))))if)@comment.save ))))))redirect_to)@comment ))))else ))))))render)action:)'new' ))))end ))end
86. https://gist.github.com/2838490#gistcomment-356060
87. class)CommentsController)<)ApplicationController ))#... )) ))def)create ))))@comment)=)@post.comments.create!(post_params) )))) ))))Notifications.new_comment(@comment).deliver )))) ))))TwitterPoster.new(current_user,)@comment.body).post ))))FacebookPoster.new(current_user,)@comment.body).post ))end
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92. class!PostComment !!def!initialize(user,!entry,!attributes) !!!!@user!=!user !!!!@entry!=!entry !!!!@attributes!=!attributes !!end ! !!def!post !!!!@comment!=!@user.comments.new !!!!@comment.assign_attributes(@attributes) !!!!@comment.entry!=!@entry !!!!@comment.save! ! !!!!LanguageDetector.new(@comment).set_language !!!!SpamChecker.new(@comment).check_spam !!!!CommentMailer.new(@comment).send_mail ! !!!!post_to_twitter!!if!@comment.share_on_twitter? !!!!post_to_facebook!if!@comment.share_on_facebook? ! !!!!@comment !!end ! !!private ! !!def!post_to_twitter !!!!PostToTwitter.new(@user,!@comment).post !!end ! !!def!post_to_facebook !!!!PostToFacebook.new(@user,!@comment).action(:comment) !!end end class!CommentsController!<!ApplicationController https://gist.github.com/2838490
93. class)CommentsController)<)ApplicationController ))#... )) ))def)create ))))context)=)PostComment.new(current_user,)@post,)post_params) ))))@comment)=)context.post ))end
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104. module)Customer ))def)add_to_cart(book) ))))self.cart)<<)book ))end end http://mikepackdev.com/blog_posts/24-the-right-way-to-code-dci-in-ruby
105. http://mikepackdev.com/blog_posts/24-the-right-way-to-code-dci-in-ruby class)AddToCart ))def)initialize(user,)book) ))))@user,)@book)=)user,)book ))))@user.extend)Customer ))end ))def)call ))))@user.add_to_cart(@book) ))end end
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