Rails 6 adds touch option to has_one association

Before Rails 6, only belongs_to association accepted touch option. When touch option is set to true, on every commit, associated object’s timestamp i.e: updated_at or updated_on will be set to current time.

After Rails 6, has_one association also accepts touch option.

class User
  has_one :profile, touch: true
end

Here is the relevant commit adding this change.