Revert "Revert "`belongs_to :touch` behavior now touches old association when transitioning to new association" until a proper fix is found for #10197"

This reverts commit 7389df139a35436f00876c96d20e81ba23c93f0a.

Conflicts:
	activerecord/test/cases/timestamp_test.rb

1 files changed, 12 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/associations/builder/belongs_to.rb b/activerecord/lib/active_record/associations/builder/belongs_to.rb
index c3026dc23c..092230b2f7 100644
--- a/activerecord/lib/active_record/associations/builder/belongs_to.rb
+++ b/activerecord/lib/active_record/associations/builder/belongs_to.rb
@@ -67,8 +67,19 @@ module ActiveRecord::Associations::Builder
     def add_touch_callbacks(reflection)
       mixin.class_eval <<-CODE, __FILE__, __LINE__ + 1
         def belongs_to_touch_after_save_or_destroy_for_#{name}
-          record = #{name}
+          foreign_key_field = #{reflection.foreign_key.inspect}
+          old_foreign_id    = attribute_was(foreign_key_field)
+
+          if old_foreign_id
+            reflection_klass = #{reflection.klass}
+            old_record       = reflection_klass.find_by(reflection_klass.primary_key => old_foreign_id)
+
+            if old_record
+              old_record.touch #{options[:touch].inspect if options[:touch] != true}
+            end
+          end
 
+          record = #{name}
           unless record.nil? || record.new_record?
             record.touch #{options[:touch].inspect if options[:touch] != true}
           end