Merge pull request rails#53957 from joshuay03/address-through-record-setting-edge-cases

Handle nested middle belongs_to, not-loaded target when setting through records

Author: byroot

activerecord/lib/active_record/associations/association.rb

@@ -193,9 +193,9 @@ def load_target
           reflections.pop
           reflections.reverse!
 
-          @target = reflections.reduce(through_association.target) do |middle_target, reflection|
+          @target = reflections.reduce(through_association.target) do |middle_target, through_reflection|
             break unless middle_target
-            middle_target.association(reflection.source_reflection_name).target
+            middle_target.association(through_reflection.source_reflection_name).load_target
           end
         end
 

activerecord/lib/active_record/associations/collection_association.rb

@@ -273,17 +273,15 @@ def load_target
         if find_target?
           @target = merge_target_lists(find_target, target)
         elsif target.empty? && set_through_target_for_new_record?
-          reflections = reflection.chain
-          reflections.pop
-          reflections.reverse!
+          reflections = reflection.chain.reverse!
 
-          @target = reflections.reduce(through_association.target) do |middle_target, reflection|
-            if middle_target.empty?
+          @target = reflections.each_cons(2).reduce(through_association.target) do |middle_target, (middle_reflection, through_reflection)|
+            if middle_target.nil? || (middle_reflection.collection? && middle_target.empty?)
               break []
-            elsif reflection.collection?
-              middle_target.flat_map { |record| record.association(reflection.source_reflection_name).target }
+            elsif middle_reflection.collection?
+              middle_target.flat_map { |record| record.association(through_reflection.source_reflection_name).load_target }
             else
-              middle_target.association(reflection.source_reflection_name).target
+              middle_target.association(through_reflection.source_reflection_name).load_target
             end
           end
         end

activerecord/lib/active_record/reflection.rb

@@ -651,6 +651,10 @@ def source_reflection
         self
       end
 
+      def source_reflection_name
+        source_reflection.name
+      end
+
       # A chain of reflections from this one back to the owner. For more see the explanation in
       # ThroughReflection.
       def collect_join_chain

activerecord/test/cases/associations/has_many_through_associations_test.rb

@@ -57,7 +57,20 @@ def setup
     Reader.create person_id: 0, post_id: 0
   end
 
-  def test_setting_association_on_new_record_sets_through_records
+  def test_setting_has_many_through_one_association_on_new_record_sets_through_records
+    account_1, account_2 = Account.create!(credit_limit: 100), Account.create!(credit_limit: 100)
+    firm = Firm.new(accounts: [account_1, account_2])
+    client = Client.new
+    client.firm = firm
+
+    assert_predicate account_1, :persisted?
+    assert_predicate account_2, :persisted?
+    assert_predicate client, :new_record?
+    assert_predicate client.firm, :new_record?
+    assert_no_queries { assert_equal [account_1, account_2].sort, client.accounts.sort }
+  end
+
+  def test_setting_has_many_through_many_association_on_new_record_sets_through_records
     subscriber_1, subscriber_2 = Subscriber.create!(nick: "nick 1"), Subscriber.create!(nick: "nick 2")
     subscription_1 = Subscription.new(subscriber: subscriber_1)
     subscription_2 = Subscription.new(subscriber: subscriber_2)
@@ -68,10 +81,42 @@ def test_setting_association_on_new_record_sets_through_records
     assert_predicate subscriber_2, :persisted?
     assert_predicate book, :new_record?
     book.subscriptions.each { |subscription| assert_predicate subscription, :new_record? }
-    assert_equal [subscriber_1, subscriber_2].sort, book.subscribers.sort
-  end
-
-  def test_setting_association_on_new_record_sets_nested_through_records
+    assert_no_queries { assert_equal [subscriber_1, subscriber_2].sort, book.subscribers.sort }
+  end
+
+  def test_setting_nested_has_many_through_one_association_on_new_record_sets_nested_through_records
+    post_tagging_1, post_tagging_2 = Tagging.create!, Tagging.create!
+    post = Post.create!(title: "Tagged", body: "Post", taggings: [post_tagging_1, post_tagging_2])
+    author = Author.new(name: "Josh")
+    author.posts = [post]
+    categorization = Categorization.new
+    categorization.author = author
+
+    assert_predicate post_tagging_1, :persisted?
+    assert_predicate post_tagging_2, :persisted?
+    assert_predicate post, :persisted?
+    assert_predicate categorization, :new_record?
+    assert_predicate categorization.author, :new_record?
+    assert_no_queries { assert_equal [post_tagging_1, post_tagging_2].sort, categorization.post_taggings.sort }
+  end
+
+  def test_setting_nested_has_many_through_one_association_on_new_record_sets_targetless_nested_through_records
+    post = Post.create!(title: "Tagged", body: "Post")
+    post_tagging_1, post_tagging_2 = Tagging.create!(taggable: post), Tagging.create!(taggable: post)
+    author = Author.new(name: "Josh")
+    author.posts = [post]
+    categorization = Categorization.new
+    categorization.author = author
+
+    assert_predicate post_tagging_1, :persisted?
+    assert_predicate post_tagging_2, :persisted?
+    assert_predicate post, :persisted?
+    assert_predicate categorization, :new_record?
+    assert_predicate categorization.author, :new_record?
+    assert_queries_count(1) { assert_equal [post_tagging_1, post_tagging_2].sort, categorization.post_taggings.sort }
+  end
+
+  def test_setting_nested_has_many_through_many_association_on_new_record_sets_nested_through_records
     account_1 = Account.create!(firm_name: "account 1", credit_limit: 100)
     subscriber_1 = Subscriber.create!(nick: "nick 1", account: account_1)
     account_2 = Account.create!(firm_name: "account 2", credit_limit: 100)
@@ -83,9 +128,11 @@ def test_setting_association_on_new_record_sets_nested_through_records
 
     assert_predicate subscriber_1, :persisted?
     assert_predicate subscriber_2, :persisted?
+    assert_predicate account_1, :persisted?
+    assert_predicate account_2, :persisted?
     assert_predicate book, :new_record?
     book.subscriptions.each { |subscription| assert_predicate subscription, :new_record? }
-    assert_equal [account_1, account_2].sort, book.subscriber_accounts.sort
+    assert_no_queries { assert_equal [account_1, account_2].sort, book.subscriber_accounts.sort }
   end
 
   def test_has_many_through_create_record

activerecord/test/cases/associations/has_one_through_associations_test.rb

@@ -23,6 +23,7 @@
 require "models/shop_account"
 require "models/customer_carrier"
 require "models/cpk"
+require "models/rating"
 
 class HasOneThroughAssociationsTest < ActiveRecord::TestCase
   fixtures :member_types, :members, :clubs, :memberships, :sponsors, :organizations, :minivans,
@@ -52,7 +53,7 @@ def test_setting_association_on_new_record_sets_through_record
     assert_predicate club, :persisted?
     assert_predicate member, :new_record?
     assert_predicate member.current_membership, :new_record?
-    assert_equal club, member.club
+    assert_no_queries { assert_equal club, member.club }
   end
 
   def test_setting_association_on_new_record_sets_nested_through_record
@@ -66,7 +67,38 @@ def test_setting_association_on_new_record_sets_nested_through_record
     assert_predicate club, :persisted?
     assert_predicate member, :new_record?
     assert_predicate member.current_membership, :new_record?
-    assert_equal club.category, member.club_category
+    assert_no_queries { assert_equal club.category, member.club_category }
+  end
+
+  def test_setting_association_on_new_record_sets_not_loaded_nested_through_record
+    category = Category.create!(name: "General")
+    club = Club.create!(category: category)
+    club.reload
+    membership = CurrentMembership.new(club: club)
+    member = Member.new
+    member.current_membership = membership
+
+    assert_predicate category, :persisted?
+    assert_predicate club, :persisted?
+    assert_predicate member, :new_record?
+    assert_predicate member.current_membership, :new_record?
+    assert_queries_count(1) { assert_equal club.category, member.club_category }
+  end
+
+  def test_setting_association_on_new_record_sets_nested_through_record_with_belongs_to
+    essay = Essay.create!
+    author = Author.create!(name: "Josh", owned_essay: essay)
+    post = Post.create!(title: "Foo", body: "Bar", author: author)
+    comment = Comment.new(post: post)
+    rating = Rating.new
+    rating.comment = comment
+
+    assert_predicate essay, :persisted?
+    assert_predicate author, :persisted?
+    assert_predicate post, :persisted?
+    assert_predicate rating, :new_record?
+    assert_predicate rating.comment, :new_record?
+    assert_no_queries { assert_equal essay, rating.owned_essay }
   end
 
   def test_creating_association_creates_through_record

activerecord/test/models/family_tree.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 class FamilyTree < ActiveRecord::Base
+  belongs_to :user
+
   belongs_to :member, class_name: "User", foreign_key: "member_id"
   belongs_to :family
 end

activerecord/test/models/member_detail.rb

@@ -5,6 +5,7 @@ class MemberDetail < ActiveRecord::Base
   belongs_to :organization
   has_one :member_type, through: :member
   has_one :membership, through: :member
+  has_one :sponsor, through: :membership
   has_one :admittable, through: :member, source_type: "Member"
 
   has_many :organization_member_details, through: :organization, source: :member_details

activerecord/test/models/membership.rb

@@ -4,6 +4,7 @@ class Membership < ActiveRecord::Base
   enum :type, %i(Membership CurrentMembership SuperMembership SelectedMembership TenantMembership)
   belongs_to :member
   belongs_to :club
+  has_one :sponsor, through: :club
 end
 
 class CurrentMembership < Membership

activerecord/test/models/post.rb

@@ -46,6 +46,7 @@ def greeting
   }
 
   belongs_to :author
+  has_one :owned_essay, through: :author
   belongs_to :readonly_author, -> { readonly }, class_name: "Author", foreign_key: :author_id
 
   belongs_to :author_with_posts, -> { includes(:posts) }, class_name: "Author", foreign_key: :author_id

activerecord/test/models/rating.rb

@@ -2,6 +2,8 @@
 
 class Rating < ActiveRecord::Base
   belongs_to :comment
+  has_one :post, through: :comment
+  has_one :owned_essay, through: :post
   has_many :taggings, as: :taggable
   has_many :taggings_without_tag, -> { left_joins(:tag).where("tags.id": [nil, 0]) }, as: :taggable, class_name: "Tagging"
   has_many :taggings_with_no_tag, -> { joins("LEFT OUTER JOIN tags ON tags.id = taggings.tag_id").where("tags.id": nil) }, as: :taggable, class_name: "Tagging"