name  |heppening

stage1|2014-02-03 12:51:00
stage2|2014-03-12 18:24:00
stage3|2014-03-29 13:12:00

timeA < happening and happening < timeB

public function configureDatagridFilters(DatagridMapper $datagridMapper)
{

    $datagridMapper
      ->add('happening');
}