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javaspringjpatransactional-database

@Transactional spring JPA .save() not necessary?

I understand that if we use annotation @Transactional. "save()" method is not necessary. Is it exact?

And for my example:

@Transactional
void methodA() {
   ...
   ObjectEntity objectEntity = objectRepository.find(); 
   methodB(objectEntity);
}

void methodB(ObjectEntity obj) {
   ...
   obj.setName("toto");
   objectRepository.save(obj);    <-- is it necessary?
}

Thanks for your help

Solution

  • It works like following:

    • save() attaches the entity to the session and at the end of the transaction as long as there were no exceptions it will all be persisted to the database.

    • Now if you get the object from the DB (e.g. ObjectEntity objectEntity = objectRepository.find();) then that object is already attached and you don't need to call the save() method.

    • If the object, however, is detached (e.g. ObjectEntity objectEntity = new ObjectEntity();) then you must use the save() method in order to attach it to the session so that changes made to it are persisted to the DB.