Merge pull request #15772 from nbudin/sti_through_bug

Don't include inheritance column in the through_scope_attributes

3 files changed, 18 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/associations/has_many_through_association.rb b/activerecord/lib/active_record/associations/has_many_through_association.rb
index 175019a72b..35e176622d 100644
--- a/activerecord/lib/active_record/associations/has_many_through_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_through_association.rb
@@ -93,7 +93,9 @@ module ActiveRecord
         end
 
         def through_scope_attributes
-          scope.where_values_hash(through_association.reflection.name.to_s).except!(through_association.reflection.foreign_key)
+          scope.where_values_hash(through_association.reflection.name.to_s).
+            except!(through_association.reflection.foreign_key,
+                    through_association.reflection.klass.inheritance_column)
         end
 
         def save_through_record(record)
diff --git a/activerecord/test/cases/associations/has_many_through_associations_test.rb b/activerecord/test/cases/associations/has_many_through_associations_test.rb
index 8641584c0c..ad2aa99af5 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -1139,4 +1139,12 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     assert_equal 2, post.lazy_readers_unscope_skimmers.to_a.size
     assert_equal 2, post.lazy_people_unscope_skimmers.to_a.size
   end
+  
+  def test_has_many_through_add_with_sti_middle_relation
+    club = SuperClub.create!(name: 'Fight Club')
+    member = Member.create!(name: 'Tyler Durden')
+
+    club.members << member
+    assert_equal 1, SuperMembership.where(member_id: member.id, club_id: club.id).count
+  end
 end
diff --git a/activerecord/test/models/club.rb b/activerecord/test/models/club.rb
index a762ad4bb5..6ceafe5858 100644
--- a/activerecord/test/models/club.rb
+++ b/activerecord/test/models/club.rb
@@ -14,3 +14,10 @@ class Club < ActiveRecord::Base
     "I'm sorry sir, this is a *private* club, not a *pirate* club"
   end
 end
+
+class SuperClub < ActiveRecord::Base
+  self.table_name = "clubs"
+
+  has_many :memberships, class_name: 'SuperMembership', foreign_key: 'club_id'
+  has_many :members, through: :memberships
+end