GraphAware\Neo4j\OGM\UnitOfWork::detectRelationshipReferenceChanges PHP Method

    public function detectRelationshipReferenceChanges()
    {
        foreach ($this->managedRelationshipReferences as $oid => $reference) {
            $entity = $this->entitiesById[$this->entityIds[$oid]];
            $reflO = $this->entityManager->getClassMetadataFor(get_class($entity));
            foreach ($reference as $field => $info) {
                $property = $reflO->getRelationship($field);
                $value = $property->getValue($entity);
                if ($value instanceof ArrayCollection || $value instanceof AbstractLazyCollection) {
                    $value = $value->toArray();
                }
                if (is_array($value)) {
                    $currentValue = array_map(function ($ref) {
                        return $this->entitiesById[$this->entityIds[$ref['target']]];
                    }, $info);
                    $compare = function ($a, $b) {
                        if ($a === $b) {
                            return 0;
                        }
                        return $a < $b ? -1 : 1;
                    };
                    $added = array_udiff($value, $currentValue, $compare);
                    $removed = array_udiff($currentValue, $value, $compare);
                    foreach ($added as $add) {
                        // Since this is the same property, it should be ok to re-use the first relationship
                        $this->scheduleRelationshipReferenceForCreate($entity, $add, $info[0]['rel']);
                    }
                    foreach ($removed as $remove) {
                        $this->scheduleRelationshipReferenceForDelete($entity, $remove, $info[0]['rel']);
                    }
                } elseif (is_object($value)) {
                    $target = $this->entitiesById[$this->entityIds[$info[0]['target']]];
                    if ($value !== $target) {
                        $this->scheduleRelationshipReferenceForDelete($entity, $target, $info[0]['rel']);
                        $this->scheduleRelationshipReferenceForCreate($entity, $value, $info[0]['rel']);
                    }
                } elseif ($value === null) {
                    foreach ($info as $ref) {
                        $target = $this->entitiesById[$this->entityIds[$ref['target']]];
                        $this->scheduleRelationshipReferenceForDelete($entity, $target, $ref['rel']);
                    }
                }
            }
        }
    }