Incompatibility with PostgreSQL

There is a problem in oa_core in function oa_core_get_parents() - the query is not wrote correctly for PostgreSQL. PostgreSQL is strict about fields types.

lines:

  $query
    ->fields('n', array('nid'))
    ->condition('f.etid', $nid);
    ->condition('f.entity_type', 'node')
    ->orderBy('n.title')
    ->addTag('node_access');

will generate DB error as PGSQL will not allow pass example word 'All' as $nid value.
instead it we can make something like:

  $query
    ->fields('n', array('nid'))
    ->condition('f.entity_type', 'node')
    ->orderBy('n.title')
    ->addTag('node_access');
  
  if(is_int($nid)) {
    $query->condition('f.etid', $nid);  
    }

This problem is in some point related to https://www.drupal.org/node/1932612 - with is still a issue in stable version of Drupal core.