backport.diff

0463698 (HEAD, 4-0-stable) Merge pull request #12646 from severin/polymorphic_belongs_to_touch [Yves Senn] [27 seconds ago]

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 852be57..adc7003 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,17 @@
+*   Polymorphic belongs_to associations with the `touch: true` option set update the timestamps of
+    the old and new owner correctly when moved between owners of different types.
+
+    Example:
+
+        class Rating < ActiveRecord::Base
+          belongs_to :rateable, polymorphic: true, touch: true
+        end
+
+        rating = Rating.create rateable: Song.find(1)
+        rating.update_attributes rateable: Book.find(2) # => timestamps of Song(1) and Book(2) are updated
+
+    *Severin Schoepke*
+
 *   Fix `last` with `offset` to return the proper record instead of always the last one.
 
     Example:
diff --git a/activerecord/lib/active_record/associations/builder/belongs_to.rb b/activerecord/lib/active_record/associations/builder/belongs_to.rb
index e8ae05d..7179726 100644
--- a/activerecord/lib/active_record/associations/builder/belongs_to.rb
+++ b/activerecord/lib/active_record/associations/builder/belongs_to.rb
@@ -73,7 +73,13 @@ module ActiveRecord::Associations::Builder
           old_foreign_id    = changed_attributes[foreign_key_field]
 
           if old_foreign_id
-            klass      = association(#{name.inspect}).klass
+            association = association(:#{name})
+            reflection = association.reflection
+            if reflection.polymorphic?
+              klass = send("#{reflection.foreign_type}_was").constantize
+            else
+              klass = association.klass
+            end
             old_record = klass.find_by(klass.primary_key => old_foreign_id)
 
             if old_record
diff --git a/activerecord/test/cases/timestamp_test.rb b/activerecord/test/cases/timestamp_test.rb
index ff1b015..f775608 100644
--- a/activerecord/test/cases/timestamp_test.rb
+++ b/activerecord/test/cases/timestamp_test.rb
@@ -224,36 +224,62 @@ class TimestampTest < ActiveRecord::TestCase
     assert_not_equal time, old_pet.updated_at
   end
 
-  def test_changing_parent_of_a_record_touches_both_new_and_old_polymorphic_parent_record
-    klass = Class.new(ActiveRecord::Base) do
-      def self.name; 'Toy'; end
+  def test_changing_parent_of_a_record_touches_both_new_and_old_polymorphic_parent_record_changes_within_same_class
+    car_class = Class.new(ActiveRecord::Base) do
+      def self.name; 'Car'; end
     end
 
-    wheel_klass = Class.new(ActiveRecord::Base) do
+    wheel_class = Class.new(ActiveRecord::Base) do
       def self.name; 'Wheel'; end
       belongs_to :wheelable, :polymorphic => true, :touch => true
     end
 
-    toy1 = klass.find(1)
-    toy2 = klass.find(2)
+    car1 = car_class.find(1)
+    car2 = car_class.find(2)
 
-    wheel = wheel_klass.new
-    wheel.wheelable = toy1
-    wheel.save!
+    wheel = wheel_class.create!(wheelable: car1)
 
     time = 3.days.ago.at_beginning_of_hour
 
-    toy1.update_columns(updated_at: time)
-    toy2.update_columns(updated_at: time)
+    car1.update_columns(updated_at: time)
+    car2.update_columns(updated_at: time)
 
-    wheel.wheelable = toy2
+    wheel.wheelable = car2
     wheel.save!
 
-    toy1.reload
-    toy2.reload
+    assert_not_equal time, car1.reload.updated_at
+    assert_not_equal time, car2.reload.updated_at
+  end
+
+  def test_changing_parent_of_a_record_touches_both_new_and_old_polymorphic_parent_record_changes_with_other_class
+    car_class = Class.new(ActiveRecord::Base) do
+      def self.name; 'Car'; end
+    end
+
+    toy_class = Class.new(ActiveRecord::Base) do
+      def self.name; 'Toy'; end
+    end
+
+    wheel_class = Class.new(ActiveRecord::Base) do
+      def self.name; 'Wheel'; end
+      belongs_to :wheelable, :polymorphic => true, :touch => true
+    end
+
+    car = car_class.find(1)
+    toy = toy_class.find(3)
+
+    wheel = wheel_class.create!(wheelable: car)
+
+    time = 3.days.ago.at_beginning_of_hour
+
+    car.update_columns(updated_at: time)
+    toy.update_columns(updated_at: time)
+
+    wheel.wheelable = toy
+    wheel.save!
 
-    assert_not_equal time, toy1.updated_at
-    assert_not_equal time, toy2.updated_at
+    assert_not_equal time, car.reload.updated_at
+    assert_not_equal time, toy.reload.updated_at
   end
 
   def test_clearing_association_touches_the_old_record