Spring data JPA and transaction management

Question

In my spring service I call two spring data repository methods

@Service
public class ClientService {
    public void updateClientByIdAndKey(final Integer id, final String key) {
        final Client client = clientRepository.findByIdAndKey(id, key);
        // .. Update client details
        client.save(client);
   }
}

Now my query is related to the transaction management. As far as I understand and have seen code, spring repositories have transactions enabled using @Transactional for its methods. For select operations it has readonly=true.

My understanding about transaction is that when select operation is executed then a transaction is created and then for the save operation another transaction is created, since for select operation transaction is readOnly=true.

I wanted both read and write operations to be executed in a single transaction. If my understanding above is correct then having @Transactional over service method updateClientByIdAndKey will run both in one transaction which is my intention or will spring execute both operation in one transaction?

Please let me know if I am missing anything here.

Answer 1

The ReadOnly property of @Transactional is defaulted to false. By simply annotating the method with Transactional both the read/select operation and the update operation will happen in a single transaction. Should you change the property to true I am guessing you will not have two transactions occurring, but instead an exception will be raised when the update is attempted.

EDIT: If the method is not annotated with Transactional both operations will not execute in a single transaction. In fact, depending on how you how configured your ORM, an exception may be thrown when executing the update as the connection will have been closed following the select.

Answer 2

When you add @Transactional annotation to your updateClientByIdAndKey method, spring will create only one read-write transaction (unless you put additional @Transactional annotation on your findByIdAndKey/save method with PROPAGATION_REQUIRES_NEW or other type of propagation. When you add readOnly = true to @Transactional spring will set flushMode on the Hibernate session will be set to NEVER. That mean you can't perform any create, update, delete operations.

Answer 3

method findByIdAndKey don't need to do COMMIT (store changes to database) and should be annotated as

@Transactional(readOnly = true)

method updateClientByIdAndKey should use

@Transactional

in updateClientByIdAndKey just one read-write Transaction is used unless your nested method findByIdAndKey defines a

@Transactional(readOnly = true, propagation = Propagation.REQUIRES_NEW)

In this case you are explicitly creating a new (readonly) Transaction that doesn't make sense.