Spring JpaRepository 不适用于事务性

Question

I have the following interface:

public interface SnapshotRepository extends JpaRepository<Snapshot, Integer>, ISnapshotRepositoryExtra { }

that as you can see extends:

public interface ISnapshotRepositoryExtra {
    Optional<Snapshot> latest();
}

... I've implemented that latest() method in the following classes:

@Transactional
public class SnapshotRepositoryExtra implements ISnapshotRepositoryExtra {

    @PersistenceContext
    private EntityManager entityManager;

    @Override
    public Optional<Snapshot> latest() {
        return (Optional<Snapshot>) entityManager
                .createQuery("SELECT r FROM snapshot r order by timestamp DESC LIMIT 1")
                .getResultStream().findFirst();
    }
}

However when I launch the project, I see:

java.lang.IllegalArgumentException: Failed to create query for method public abstract java.util.Optional com...persistance.snapshot.ISnapshotRepositoryExtra.latest()! No property latest found for type Snapshot!

So my question is, why Spring does not see the class SnapshotRepositoryExtra that I've just made?

Answer 1

Spring Data is picky about how you name things. According to the documentation :

The most important part of the class name that corresponds to the fragment interface is the Impl postfix.

In other words, you need to call your interface something like SnapshotRepositoryExtra and the implementation SnapshotRepositoryExtraImpl for Spring Data to recognise it (most examples I've seen would use something like CustomSnapshotRepository for the interface, but I don't think that convention is required).

That's for the latest version; previous versions of Spring Data had different naming requirements .