use Sonata\AdminBundle\Datagrid\ListMapper; class UserAdmin extends AbstractAdmin { protected function configureListFields(ListMapper $listMapper) { $listMapper ->addIdentifier('username') ->add('email'); } }In this example, the addIdentifier() method specifies that the "username" field should be used as the primary identifier for each user, and add() adds the "email" field as a separate column in the list. Overall, ListMapper is a powerful tool for customizing the behavior and appearance of admin panels in Symfony projects using the SonataAdminBundle library.