Doctrine\ODM\MongoDB\Persisters\PersistenceBuilder::prepareInsertData PHP Method

    public function prepareInsertData($document)
    {
        $oid = spl_object_hash($document);
        $class = $this->dm->getClassMetadata(get_class($document));
        $changeset = $this->uow->getDocumentChangeSet($document);
        $insertData = array();
        foreach ($class->fieldMappings as $mapping) {
            // many collections are inserted later
            if ($mapping['type'] === 'many') {
                continue;
            }
            // skip not saved fields
            if (isset($mapping['notSaved']) && $mapping['notSaved'] === true) {
                continue;
            }
            // Skip version and lock fields
            if (isset($mapping['version']) || isset($mapping['lock'])) {
                continue;
            }

            $new = isset($changeset[$mapping['fieldName']][1]) ? $changeset[$mapping['fieldName']][1] : null;

            // Prepare new document identifier
            if ($class->isIdentifier($mapping['fieldName'])) {
                if ( ! $class->isIdGeneratorNone() && $new === null) {
                    $new = $class->idGenerator->generate($this->dm, $document);
                }
                $insertData['_id'] = Type::getType($mapping['type'])->convertToDatabaseValue($new);
                continue;
            }
            // Skip null values
            if ($new === null && $mapping['nullable'] === false) {
                continue;
            }
            $value = $this->prepareValue($mapping, $new);

            // Check if a reference is not persisted yet and we need to schedule an extra update
            $insertData[$mapping['name']] = $value;
            if (isset($mapping['reference'])) {
                $scheduleForUpdate = false;
                if ($mapping['type'] === 'one') {
                    if ( ! isset($insertData[$mapping['name']][$this->cmd . 'id'])) {
                        $scheduleForUpdate = true;
                    }
                }
                if ($scheduleForUpdate) {
                    unset($insertData[$mapping['name']]);
                    $this->uow->scheduleExtraUpdate($document, array(
                        $mapping['fieldName'] => array(null, $new)
                    ));
                }
            }
        }
        // add discriminator if the class has one
        if ($class->hasDiscriminator()) {
            $insertData[$class->discriminatorField['name']] = $class->discriminatorValue;
        }
        return $insertData;
    }

 /**
  * Executes all queued document insertions.
  *
  * Queued documents without an ID will inserted in a batch and queued
  * documents with an ID will be upserted individually.
  *
  * If no inserts are queued, invoking this method is a NOOP.
  *
  * @param array $options Options for batchInsert() and update() driver methods
  */
 public function executeInserts(array $options = array())
 {
     if (!$this->queuedInserts) {
         return;
     }
     $inserts = array();
     foreach ($this->queuedInserts as $oid => $document) {
         $data = $this->pb->prepareInsertData($document);
         // Set the initial version for each insert
         if ($this->class->isVersioned) {
             $versionMapping = $this->class->fieldMappings[$this->class->versionField];
             if ($versionMapping['type'] === 'int') {
                 $nextVersion = $this->class->reflFields[$this->class->versionField]->getValue($document);
                 $this->class->reflFields[$this->class->versionField]->setValue($document, $nextVersion);
             } elseif ($versionMapping['type'] === 'date') {
                 $nextVersionDateTime = new \DateTime();
                 $nextVersion = new \MongoDate($nextVersionDateTime->getTimestamp());
                 $this->class->reflFields[$this->class->versionField]->setValue($document, $nextVersionDateTime);
             }
             $data[$versionMapping['name']] = $nextVersion;
         }
         $inserts[$oid] = $data;
     }
     if ($inserts) {
         try {
             $this->collection->batchInsert($inserts, $options);
         } catch (\MongoException $e) {
             $this->queuedInserts = array();
             throw $e;
         }
     }
     $this->queuedInserts = array();
 }