Active Record Association (2), Season 2

1. Ror lab. season 2 - the 9th round - Active Record Associations (2) November 3rd, 2012 Hyoseong Choi

2. Association Options belongs_to options has_one options has_many options HABTM options • :autosave • :autosave • :autosave • :autosave • :class_name • :class_name • :class_name • :class_name • :conditions • :conditions • :conditions • :conditions • :foreign_key • :foreign_key • :foreign_key • :foreign_key • :include • :include • :include • :include • :readonly • :readonly • :readonly • :readonly • :select • :select • :select • :select • :validate • :validate • :validate • :validate • :dependent • :as • :as • :order • :counter_cache • :order • :order • :counter_sql • :polymorphic • :primary_key • :primary_key • :extend • :touch • :source • :source • :finder_sql • :source_type • :source_type • :group • :through • :through • :limit • :dependent • :counter_sql • :offset • :extend • :uniq • :finder_sql • :association_foreign_key • :group • :delete_sql • :limit • :insert_sql • :offset • :join_table • :uniq • :dependent

10. Common Options • :autosave • :class_name • :conditions • :foreign_key • :include • :readonly • :select • :validate

11. - common options - :autosave • No declaration (default) : new children are saved when their parent is saved • :autosave => true : all children is saved, no matter whether they are new records • :autosave => false : any children is not saved

12. - common options - :autosave class Post has_one :author, :autosave => true end has_one post = Post.find(1) post.title # => "The current global position of migrating ducks" post.author.name # => "alloy" post.title = "On the migration of ducks" post.author.name = "Eloy Duran" post.save post.reload post.title # => "On the migration of ducks" post.author.name # => "Eloy Duran" post.author.mark_for_destruction post.author.marked_for_destruction? # => true id = post.author.id Author.find_by_id(id).nil? # => false post.save post.reload.author # => nil Author.find_by_id(id).nil? # => true http://api.rubyonrails.org/classes/ActiveRecord/AutosaveAssociation.html

13. - common options - :autosave has_many class Post has_many :comments # :autosave option is no declared end post = Post.new(:title => 'ruby rocks') post.comments.build(:body => 'hello world') post.save # => saves both post and comment post = Post.create(:title => 'ruby rocks') post.comments.build(:body => 'hello world') post.save # => saves both post and comment post = Post.create(:title => 'ruby rocks') post.comments.create(:body => 'hello world') post.save # => saves both post and comment class Post has_many :comments, :autosave => true end post = Post.create(:title => 'ruby rocks') post.comments.create(:body => 'hello world') post.comments[0].body = 'hi everyone' post.save # => saves both post and comment, with 'hi everyone' as body post.comments.last.mark_for_destruction post.comments.last.marked_for_destruction? # => true post.comments.length # => 2 id = post.comments.last.id Comment.find_by_id(id).nil? # => false post.save post.reload.comments.length # => 1 Comment.find_by_id(id).nil? # => true

14. - common options - :class_name class Order < ActiveRecord::Base belongs_to :customer, :class_name => "Patron" end

15. - common options - :conditions class Order < ActiveRecord::Base belongs_to :customer, :conditions => "active = 1" end

16. - common options - :foreign_key class Order < ActiveRecord::Base belongs_to :customer, :class_name => "Patron", :foreign_key => "patron_id" end

17. - common options - :include @line_item.order.customer class LineItem < ActiveRecord::Base belongs_to :order, :include => :customer end class Order < ActiveRecord::Base belongs_to :customer has_many :line_items end class Customer < ActiveRecord::Base has_many :orders end

18. - common options - :readonly class Customer < ActiveRecord::Base has_many :orders, :readonly => true end

19. - common options - :select class Order < ActiveRecord::Base belongs_to :customer, :select => "name, proﬁle, group_id" end

20. - common options - :validate class Order < ActiveRecord::Base belongs_to :customer, :validate => true end

21. Common has_ Options has_one / has_many • :as • :order* (also, included in HABTM) • :primary_key • :source • :source_type • :through

22. - common has_ options - :as class Employee < ActiveRecord::Base has_many :pictures, :as => :imageable end class Product < ActiveRecord::Base has_many :pictures, :as => :imageable end class Picture < ActiveRecord::Base belongs_to :imageable, :polymorphic => true end

23. - common has_ options - :order class Post < ActiveRecord::Base has_many :comments, :order => ”updated_at” end •also, in HABTM

24. - common has_ options - :primary_key class Customer < ActiveRecord::Base default has_many :orders, :primary_key => "id", :foreign_key => "customer_id" class Customer < ActiveRecord::Base has_many :orders :primary_key => "order_id", :foreign_key => "patron_id"

25. - common has_ options - :primary_key class Order < ActiveRecord::Base default belongs_to :customer, :primary_key => "id", :foreign_key => "customer_id" class Order < ActiveRecord::Base belongs_to :customer, :class_name => "Patron", :primary_key => "civil_no", :foreign_key => "patron_id"

26. - common has_ options - :source & :source_type class Book < ActiveRecord::Base has_many :taggings has_many :tags, :through => :taggings end class Tag < ActiveRecord::Base has_many :taggings has_many :books, :through => :taggings end class Tagging < ActiveRecord::Base belongs_to :book belongs_to :tag join model end - Basic many-to-many association format

27. - common has_ options - :source & :source_type class Movie < ActiveRecord::Base has_many :taggings, :as => :taggable class Book < ActiveRecord::Base has_many :taggings, :as has_many :tags, :through => :taggings => :taggable end has_many :tags, :through => :taggings end class Tagging < ActiveRecord::Base belongs_to :taggble, :polymorphic => true belongs_to :tag end class Tag < ActiveRecord::Base has_many :taggings has_many :taggables, :through => :taggings end - Polymorphic many-to-many association format

28. - common has_ options - :source & :source_type class Book < ActiveRecord::Base has_many :taggings, :as => :taggable class Movie < ActiveRecord::Base has_many :tags, :through => :taggings has_many :taggings, :as => :taggable end has_many :tags, :through => :taggings end class Tagging < ActiveRecord::Base belongs_to :taggble, :polymorphic => true belongs_to :tag end class Tag < ActiveRecord::Base has_many :taggings has_many :taggables, :through => :taggings has_many :books, :source => :taggable, :source_type => “Book”, :through => :taggings has_many :movies, :source => :taggable, :source_type => “Movie”, :through => :taggings end - Polymorphic many-to-many association format

29. - common has_ options - :source & :source_type class Tag < ActiveRecord::Base has_many :taggings, :dependent => :destroy has_many :books, :through => :taggings, :source => :taggable, :source_type => "Book" has_many :movies, :through => :taggings, :source => :taggable, :source_type => "Movie" end class Tagging < ActiveRecord::Base belongs_to :taggable, :polymorphic => true belongs_to :tag end class Book < ActiveRecord::Base has_many :taggings, :as => :taggable has_many :tags, :through => :taggings end class Movie < ActiveRecord::Base has_many :taggings, :as => :taggable has_many :tags, :through => :taggings end - Polymorphic many-to-many association format

30. - common has_ options - :through class Supplier < ActiveRecord::Base has_one :account has_one :account_history, :through => :account end class Account < ActiveRecord::Base belongs_to :supplier has_one :account_history end class AccountHistory < ActiveRecord::Base belongs_to :account end

31. Common _many Options has_many / HABTM • :counter_sql • :extend • :ﬁnder_sql • :group • :limit • :offset • :uniq

32. - common _many options - :finder_sql class Person < ActiveRecord::Base has_many :subscribers, :class_name => "Person", :finder_sql => Proc.new { %Q{ SELECT DISTINCT * FROM people p, post_subscriptions ps WHERE ps.post_id = #{id} AND ps.person_id = p.id ORDER BY p.first_name } }

33. - common _many options - :counter_sql class Person < ActiveRecord::Base has_many :subscribers, :class_name => "Person", :counter_sql => Proc.new { %Q{ SELECT DISTINCT * FROM people p, post_subscriptions ps WHERE ps.post_id = #{id} AND ps.person_id = p.id ORDER BY p.ﬁrst_name } }

34. - common _many options - :extend association proxy(or interface) class Customer < ActiveRecord::Base has_many :orders do def find_by_order_prefix(order_number) find_by_region_id(order_number[0..2]) end end

35. - common _many options - :extend module FindRecentExtension def ﬁnd_recent where("created_at > ?", 5.days.ago) end end class Customer < ActiveRecord::Base has_many :orders, :extend => FindRecentExtension end class Supplier < ActiveRecord::Base has_many :deliveries, :extend => FindRecentExtension

36. - common _many options - :extend class Customer < ActiveRecord::Base has_many :orders, :extend => [FindRecentExtension, FindActiveExtension] end

37. - common _many options - * 3 AP accessors • proxy_association.owner • proxy_association.reﬂection • proxy_association.target AP* : Association Proxy

38. - common _many options - :group class Customer < ActiveRecord::Base has_many :line_items, :through => :orders, :group => "orders.id" end

39. - common _many options - :limit / :offset class Customer < ActiveRecord::Base has_many :recent_orders, :class_name => "Order", :order => "order_date DESC", :limit => 100 :offset => 300

40. - common _many options - :uniq class Person < ActiveRecord::Base has_many :readings has_many :posts, :through => :readings end person = Person.create(:name => 'john') post = Post.create(:name => 'a1') person.posts << post person.posts << post person.posts.inspect # => [#<Post id: 5, name: "a1">, #<Post id: 5, name: "a1">] Reading.all.inspect # => [#<Reading id: 12, person_id: 5, post_id: 5>, #<Reading id: 13, person_id: 5, post_id: 5>]

41. - common _many options - :uniq class Person has_many :readings has_many :posts, :through => :readings, :uniq => true end person = Person.create(:name => 'honda') post = Post.create(:name => 'a1') person.posts << post person.posts << post person.posts.inspect # => [#<Post id: 7, name: "a1">] Reading.all.inspect # => [#<Reading id: 16, person_id: 7, post_id: 7>, #<Reading id: 17, person_id: 7, post_id: 7>]

42. Common one-way Options belongs_to / has_one / has_many • :dependent class Comment < ActiveRecord::Base belongs_to :post, :dependent => :destroy end class Post < ActiveRecord::Base has_many :comments, :dependent => :destroy end

43. Special Options • belongs_to • :counter_cache • :polymorphic • :touch • HABTM • :association_foreign_key • :delete_sql • :insert_sql • :join_table

44. - special options for HABTM - :association_foreign_key class User < ActiveRecord::Base has_and_belongs_to_many :friends, :class_name => "User", :foreign_key => "this_user_id", :association_foreign_key => "other_user_id" many-to-many self join

45. - special options for HABTM - :delete_sql class Developer < ActiveRecord::Base has_and_belongs_to_many :active_projects, :join_table => 'developers_projects', :delete_sql => "DELETE FROM developers_projects WHERE active=1 AND developer_id = #{id} AND project_id = #{record.id}" end

46. - special options for HABTM - :insert_sql class Developer < ActiveRecord::Base has_and_belongs_to_many :active_projects, :join_table => 'developers_projects', :insert_sql => "INSERT INTO developers_projects VALUES(#{id},#{record.id})" end

47. - special options for HABTM - :join_table class Category < ActiveRecord::Base has_and_belongs_to_many :products, :join_table => “cats_prods” end class Product < ActiveRecord::Base has_and_belongs_to_many :categories, :join_table => “cats_prods” default join table => “categories_products”

48. Association Callbacks • in the lifecycle of a collection • before_add • after_add • before_remove • after_remove

49. Association Callbacks class Customer < ActiveRecord::Base has_many :orders, :before_add => :check_credit_limit def check_credit_limit(order) ... end end class Customer < ActiveRecord::Base has_many :orders, :before_add => [:check_credit_limit, :calculate_shipping_charges] def check_credit_limit(order) ... end def calculate_shipping_charges(order) ... end

50. Summary • http://jonathanhui.com/ruby-rails-3-model- association

51. 감사합니다.

52. ROR Lab.

Active Record Association (2), Season 2

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Editor's Notes