Fix ActiveRecord locking column defaults not getting persisted

When partial inserts are enabled, overridden db defaults are ignored. This
results in locking columns having a nil value for new records if the db default
is null. This happens because the list of changed attributes for new records is
always assumed to be empty.

Solution: When a new record's default attributes are set, also initialize the
list of changed attributes by comparing current values against what's stored as
the column defaults in the database.

1 files changed, 8 insertions, 0 deletions

diff --git a/activerecord/test/cases/locking_test.rb b/activerecord/test/cases/locking_test.rb
index 0c896beb1d..77891b9156 100644
--- a/activerecord/test/cases/locking_test.rb
+++ b/activerecord/test/cases/locking_test.rb
@@ -193,11 +193,19 @@ class OptimisticLockingTest < ActiveRecord::TestCase
   def test_lock_without_default_sets_version_to_zero
     t1 = LockWithoutDefault.new
     assert_equal 0, t1.lock_version
+
+    t1.save
+    t1 = LockWithoutDefault.find(t1.id)
+    assert_equal 0, t1.lock_version
   end
 
   def test_lock_with_custom_column_without_default_sets_version_to_zero
     t1 = LockWithCustomColumnWithoutDefault.new
     assert_equal 0, t1.custom_lock_version
+
+    t1.save
+    t1 = LockWithCustomColumnWithoutDefault.find(t1.id)
+    assert_equal 0, t1.custom_lock_version
   end
 
   def test_readonly_attributes