Merge pull request #48674 from gmcgibbon/hmt_singular_fix

Fix has_one through singular building with inverse.

activerecord/CHANGELOG.md

@@ -1,3 +1,12 @@
+*   Fix has_one through singular building with inverse.
+
+    Allows building of records from an association with a has_one through a
+    singular association with inverse. For belongs_to through associations,
+    linking the foreign key to the primary key model isn't needed.
+    For has_one, we cannot build records due to the association not being mutable.
+
+    *Gannon McGibbon*
+
 *   Disable database prepared statements when query logs are enabled
 
     Prepared Statements and Query Logs are incompatible features due to query logs making every query unique.

activerecord/lib/active_record/associations/through_association.rb

@@ -114,12 +114,14 @@ def ensure_not_nested
         end
 
         def build_record(attributes)
-          inverse = source_reflection.inverse_of
-          target = through_association.target
+          if source_reflection.collection?
+            inverse = source_reflection.inverse_of
+            target = through_association.target
 
-          if inverse && target && !target.is_a?(Array)
-            Array(target.id).zip(Array(inverse.foreign_key)).map do |primary_key_value, foreign_key_column|
-              attributes[foreign_key_column] = primary_key_value
+            if inverse && target && !target.is_a?(Array)
+              Array(target.id).zip(Array(inverse.foreign_key)).map do |primary_key_value, foreign_key_column|
+                attributes[foreign_key_column] = primary_key_value
+              end
             end
           end
 

activerecord/test/cases/associations/has_one_through_associations_test.rb

@@ -100,6 +100,14 @@ def test_building_multiple_associations_builds_through_record
     assert_predicate member_detail_with_two_associations.member, :new_record?
   end
 
+  def test_building_works_with_has_one_through_belongs_to
+    new_member = Member.create!(name: "Joe")
+    new_member.create_current_membership!
+    new_club = new_member.build_club
+
+    assert_equal(new_member.club, new_club)
+  end
+
   def test_creating_multiple_associations_creates_through_record
     member_type = MemberType.create!
     member = Member.create!

activerecord/test/models/membership.rb

@@ -8,7 +8,7 @@ class Membership < ActiveRecord::Base
 
 class CurrentMembership < Membership
   belongs_to :member
-  belongs_to :club
+  belongs_to :club, inverse_of: :membership
 end
 
 class SuperMembership < Membership