如何刷新教义中的子对象

Question

I have 2 table property and property_type

property's columns: id, name, property_type_id, style, ...., status, create_at, update_at

property_type's columns: id, name, status, create_at, update_at

property_type_id column is mapping with property_type table

Here my code

    $entityManager = $this->getDoctrine()->getManager();
    $propertyData = $entityManager->getRepository('PropertyBundle:Property')->find(4);
    $propertyType = $propertyData->getPropertyTypeId();

    if($propertyData->getStatus() == 1) {
        $propertyData->setName('test1');
        $propertyType->setName('test1');
    } else if($propertyData->getStatus() == 2) {
        $propertyData->setName('test2');
        $propertyType->setName('test2');
    }

   if($propertyData->getStyle() == 1) {
       // only refresh $propertyType object
        $entityManager->refresh($propertyType) 
    }

I am trying to refresh only $propertyType but according above code $propertyType and $propertyData both objects are getting refreshed.