Doctrine\ODM\MongoDB\Mapping\ClassMetadataInfo::getFieldNames PHP Method

    public function getFieldNames()
    {
        return array_keys($this->fieldMappings);
    }

 /**
  * Returns an array of fields. Fields can be both column fields and
  * association fields.
  *
  * @param \Doctrine\ODM\MongoDB\Mapping\ClassMetadataInfo $metadata
  *
  * @return array
  */
 private function getFieldsFromMetadata(ClassMetadataInfo $metadata)
 {
     $fields = (array) $metadata->getFieldNames();
     // Remove the primary key field if it's not managed manually
     if ($metadata->isIdGeneratorAuto()) {
         $fields = array_diff($fields, array($metadata->identifier));
     }
     return $fields;
 }