Merge pull request #14979 from brocktimus/master

Making belongs_to: touch behaviour be consistent with save updating updated_at

3 files changed, 16 insertions, 1 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index c824cf1c58..283ca33913 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,11 @@
+*   Change belongs_to touch to be consistent with timestamp updates
+
+    If a model is set up with a belongs_to: touch relatinoship the parent
+    record will only be touched if the record was modified. This makes it
+    consistent with timestamp updating on the record itself.
+
+    *Brock Trappitt*
+
 *   Fixed the inferred table name of a HABTM auxiliar table inside a schema.
 
     Fixes #14824
diff --git a/activerecord/lib/active_record/associations/builder/belongs_to.rb b/activerecord/lib/active_record/associations/builder/belongs_to.rb
index 47cc1f4b34..3998aca23e 100644
--- a/activerecord/lib/active_record/associations/builder/belongs_to.rb
+++ b/activerecord/lib/active_record/associations/builder/belongs_to.rb
@@ -103,7 +103,7 @@ module ActiveRecord::Associations::Builder
         BelongsTo.touch_record(record, foreign_key, n, touch)
       }
 
-      model.after_save    callback
+      model.after_save    callback, if: :changed?
       model.after_touch   callback
       model.after_destroy callback
     end
diff --git a/activerecord/test/cases/associations/belongs_to_associations_test.rb b/activerecord/test/cases/associations/belongs_to_associations_test.rb
index 3b484a0d64..dc7314b450 100644
--- a/activerecord/test/cases/associations/belongs_to_associations_test.rb
+++ b/activerecord/test/cases/associations/belongs_to_associations_test.rb
@@ -369,6 +369,13 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert_queries(2) { line_item.update amount: 10 }
   end
 
+  def test_belongs_to_with_touch_option_on_empty_update
+    line_item = LineItem.create!
+    Invoice.create!(line_items: [line_item])
+
+    assert_queries(0) { line_item.save }
+  end
+
   def test_belongs_to_with_touch_option_on_destroy
     line_item = LineItem.create!
     Invoice.create!(line_items: [line_item])