When you add a record to a polymorphic has_one, you should be able to access the owner from the associated record

3 files changed, 6 insertions, 3 deletions

diff --git a/activerecord/lib/active_record/associations/association.rb b/activerecord/lib/active_record/associations/association.rb
index 687b668634..0ccf74c7a4 100644
--- a/activerecord/lib/active_record/associations/association.rb
+++ b/activerecord/lib/active_record/associations/association.rb
@@ -141,7 +141,7 @@ module ActiveRecord
             @target ||= find_target
           end
         end
-        loaded!
+        loaded! unless loaded?
         target
       rescue ActiveRecord::RecordNotFound
         reset
diff --git a/activerecord/lib/active_record/associations/has_one_association.rb b/activerecord/lib/active_record/associations/has_one_association.rb
index 2f3a6e71f1..6b8201973a 100644
--- a/activerecord/lib/active_record/associations/has_one_association.rb
+++ b/activerecord/lib/active_record/associations/has_one_association.rb
@@ -14,8 +14,8 @@ module ActiveRecord
           end
 
           if record
-            set_inverse_instance(record)
             set_owner_attributes(record)
+            set_inverse_instance(record)
 
             if owner.persisted? && save && !record.save
               nullify_owner_attributes(record)
diff --git a/activerecord/test/cases/associations/join_model_test.rb b/activerecord/test/cases/associations/join_model_test.rb
index b59ce4efeb..785ea079ed 100644
--- a/activerecord/test/cases/associations/join_model_test.rb
+++ b/activerecord/test/cases/associations/join_model_test.rb
@@ -139,7 +139,10 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
   def test_set_polymorphic_has_one
     tagging = tags(:misc).taggings.create
     posts(:thinking).tagging = tagging
-    assert_equal "Post", tagging.taggable_type
+
+    assert_equal "Post",              tagging.taggable_type
+    assert_equal posts(:thinking).id, tagging.taggable_id
+    assert_equal posts(:thinking),    tagging.taggable
   end
 
   def test_create_polymorphic_has_many_with_scope