Make deleting with optimistic locking respect NULL

For now deleting with optimistic locking is broken when
lock_version is still NULL, because Rails would try to
delete with `lock_version = 0` while in the database
the column is still `NULL`.

The monkey patches would force Rails just pass whatever
in the column, and stop Rails from casting `NULL` into `0`
when the value is read from database.

Closes #24766

1 files changed, 18 insertions, 0 deletions

diff --git a/config/initializers/ar_monkey_patch.rb b/config/initializers/ar_monkey_patch.rb
index 0da584626ee..5506873344f 100644
--- a/config/initializers/ar_monkey_patch.rb
+++ b/config/initializers/ar_monkey_patch.rb
@@ -52,6 +52,24 @@ module ActiveRecord
           raise
         end
       end
+
+      # This is patched because we need it to query `lock_version IS NULL`
+      # rather than `lock_version = 0` whenever lock_version is NULL.
+      def relation_for_destroy
+        return super unless locking_enabled?
+
+        column_name = self.class.locking_column
+        table_name =  self.class.quoted_table_name
+        super.where("#{table_name}.#{column_name}" => self[column_name])
+      end
+    end
+
+    # This is patched because we want `lock_version` default to `NULL`
+    # rather than `0`
+    class LockingType < SimpleDelegator
+      def type_cast_from_database(value)
+        super
+      end
     end
   end
 end