RISReferenceNormalizer.php in Bibliography & Citation 2.0.x        
                          
                  
                        
  
  
  
  
File
  modules/bibcite_ris/src/Normalizer/RISReferenceNormalizer.php
  
    View source  
  <?php
namespace Drupal\bibcite_ris\Normalizer;
use Drupal\bibcite_entity\Entity\ReferenceInterface;
use Drupal\bibcite_entity\Normalizer\ReferenceNormalizerBase;
class RISReferenceNormalizer extends ReferenceNormalizerBase {
  
  protected function extractFields(ReferenceInterface $reference, $format) {
    $attributes = parent::extractFields($reference, $format);
    $isbn = $this
      ->extractScalar($reference
      ->get('bibcite_isbn'));
    $issn = $this
      ->extractScalar($reference
      ->get('bibcite_issn'));
    if ($isbn || $issn) {
      $attributes['SN'] = trim($isbn . '/' . $issn, '/');
    }
    return $attributes;
  }
}