Clear locking column on #dup

When duplicating records, we usually want to create a new record and
don't want to keep the original lock_version. Just like timestamp
columns are not copied.

Co-authored-by: Seonggi Yang <seonggi.yang@gmail.com>
Co-authored-by: Ryohei UEDA <ueda@anipos.co.jp>

activerecord/CHANGELOG.md

@@ -1,3 +1,16 @@
+*   Clear locking column on #dup
+
+    This change fixes not to duplicate locking_column like id and timestamps.
+
+    ```
+    car = Car.create!
+    car.touch
+    car.lock_version #=> 1
+    car.dup.lock_version #=> 0
+    ```
+
+    *Shouichi Kamiya*, *Seonggi Yang*, *Ryohei UEDA*
+
 *   Allow configuring columns list to be used in SQL queries issued by an `ActiveRecord::Base` object
 
     It is now possible to configure columns list that will be used to build an SQL query clauses when

activerecord/lib/active_record/core.rb

@@ -517,7 +517,8 @@ def init_with_attributes(attributes, new_record = false) # :nodoc:
     # only, not its associations. The extent of a "deep" copy is application
     # specific and is therefore left to the application to implement according
     # to its need.
-    # The dup method does not preserve the timestamps (created|updated)_(at|on).
+    # The dup method does not preserve the timestamps (created|updated)_(at|on)
+    # and locking column.
 
     ##
     def initialize_dup(other) # :nodoc:

activerecord/lib/active_record/locking/optimistic.rb

@@ -69,6 +69,11 @@ def increment!(*, **) # :nodoc:
         end
       end
 
+      def initialize_dup(other) # :nodoc:
+        super
+        _clear_locking_column if locking_enabled?
+      end
+
       private
         def _create_record(attribute_names = self.attribute_names)
           if locking_enabled?
@@ -142,6 +147,11 @@ def _lock_value_for_database(locking_column)
           end
         end
 
+        def _clear_locking_column
+          self[self.class.locking_column] = nil
+          clear_attribute_change(self.class.locking_column)
+        end
+
         module ClassMethods
           DEFAULT_LOCKING_COLUMN = "lock_version"
 

activerecord/test/cases/dup_test.rb

@@ -4,10 +4,11 @@
 require "models/reply"
 require "models/topic"
 require "models/movie"
+require "models/car"
 
 module ActiveRecord
   class DupTest < ActiveRecord::TestCase
-    fixtures :topics
+    fixtures :topics, :cars
 
     def test_dup
       assert_not_predicate Topic.new.freeze.dup, :frozen?
@@ -118,6 +119,27 @@ def test_dup_timestamps_are_cleared
       assert_not_nil new_topic.created_at
     end
 
+    def test_dup_locking_column_is_cleared
+      car = Car.first
+      car.touch
+      assert_not_equal 0, car.lock_version
+
+      car.lock_version = 1000
+
+      new_car = car.dup
+      assert_equal 0, new_car.lock_version
+    end
+
+    def test_dup_locking_column_is_not_dirty
+      car = Car.first
+      car.touch
+      assert_not_equal 0, car.lock_version
+
+      car.lock_version += 1
+      new_car = car.dup
+      assert_not_predicate new_car, :lock_version_changed?
+    end
+
     def test_dup_after_initialize_callbacks
       topic = Topic.new
       assert Topic.after_initialize_called