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Hibernate 6.3.0 (and 6.2.8)

Posted by    |       Hibernate ORM Releases

Hibernate ORM 6.3.0 has just been released. Simultaneously, 6.2.8 has also been released.

NOTE

With the release of 6.3.0, 6.2 now moves into limited maintenance.

Jakarta Persistence 3.2

Jakarta Persistence 3.2 is still under development, but we’ve already begun incorporating some of the changes into Hibernate.

One specific change to be aware of in 6.3 is the clarification with regard to types of numeric literals in HQL/JPQL queries. You can check out the details, but the gist is -

  • Integer - 123

  • Long - 123l, 123L

  • BigInteger - 123bi, 123BI

  • Double - 123.4

  • Float literal - 123.4f, 123.4F

  • BigDecimal literal - 123.4bd, 123.4BD

Notice that Hibernate’s BigInteger and BigDecimal suffix synatx has been standardized also.

New documentation artifacts

2 new documentation guides have been added -

  1. An introductory Hibernate 6 Guide

  2. The Hibernate Query Language synatx and feature guide

Query methods

Hibernate can now generate DAO-style methods for named queries as part of its JPA static metamodel generator.

Take the following entity as an example:

@NamedQuery(name = "#findByTitleAndType",
        query = "select book from Book book where book.title like :titlePattern and book.type = :type")
@Entity
public class Book { ... }

When processed by the metamodel generator, Hibernate adds the following into the static metamodel:

class Book_ {
    // as normal
    ...

    public static final String QUERY_FIND_BY_TITLE_AND_TYPE = "#findByTitleAndType";

    public static List<Book> findByTitleAndType(@Nonnull EntityManager entityManager, String titlePattern, Type type) {
        return entityManager.createNamedQuery(QUERY_FIND_BY_TITLE_AND_TYPE)
                .setParameter("titlePattern", titlePattern)
                .setParameter("type", type)
                .getResultList();
    }
}

And the application can then use:

List<Book> books =
        Book_.findByTitleAndType(entityManager, titlePattern, Type.BOOK);

There are a lot of capabilities to these query methods; see the Hibernate 6 Guide for a full discussion.

Finder methods

Using the new @Find annotation, arbitrary methods can now be processed by the generator to create finder methods similar to query methods.

interface Dao {
    @Find
    Book findBookByIsbn(String isbn);
}

The generator will generate:

class Dao_ {
        public static Book findBookByIsbn(@Nonnull EntityManager entityManager, String isbn) {
                return entityManager.unwrap(Session.class)
                                .byNaturalId(Book.class)
                                .using(Book_.isbn, isbn)
                                .load();
        }
}

Again, there are a lot of capabilities to these finder methods; see the Hibernate 6 Guide for a full discussion.

Dynamic SUBSELECT fetch support

Hibernate’s SUBSELECT fetching style can now be applied dynamically using fetch profiles. E.g.

@FetchProfile(name = "EagerBook")
@FetchProfile(name = "EagerBookWithSubselect")
@Entity
class Book {
    ...

    @ManyToMany
    @FetchProfileOverride(profile = Book_.PROFILE_EAGER_BOOK, mode = JOIN)
    @FetchProfileOverride(profile = Book_.PROFILE_EAGER_BOOK_WITH_SUBSELECT, mode = SUBSELECT)
    Set<Author> authors;
}

Then, at runtime we can pick between these profiles to control how the associations are loaded -

Session session = ...;

session.enableFetchProfile( Book_.PROFILE_EAGER_BOOK );
// or
session.enableFetchProfile( Book_.PROFILE_EAGER_BOOK_WITH_SUBSELECT );
NOTE

What’s up with those Book_.PROFILE_EAGER_BOOK references? See the Hibernate 6 Guide

Create Criteria from HQL

6.3 adds the abillity to create a Criteria reference from HQL -

var builder = session.getFactory().getCriteriaBuilder();
var hqlCriteria = session.getFactory()
        .getCriteriaBuilder()
        .createQuery( "select id, text from Message order by received", Object[].class );

which can be mutated just like any Criteria…​

var root = hqlCriteria.getRootList().get(0)
root.where(
    builder.equal(
        root.get(Message_.deleted),
        'Y'
    )
);

CriteriaDefinition utility

The new CriteriaDefinition class is a utility for making it easier to work with Jakarta Persistence Criterias in many case. E.g.

var query = new CriteriaDefinition<>(factory, Message.class) {{
    var message = from(Message.class);
    where(like(message.get("text"), "hell%"), message.get("id").equalTo(1));
    orderBy(asc(message.get("id")));
}};

Session session = ...;
var message = session.createSelectionQuery(query).getSingleResult();

We can even use this to clean up the example from Create Criteria from HQL -

var query = new CriteriaDefinition<>(factory, Object[].class, "select id, text from Message order by received") {{
    var root = getRootList().get(0);
    where( equal( root.get(Message_.deleted), 'Y' );
}};

StatelessSession.upsert()

The new StatelessSession.upsert() method allows performing SQL-style UPSERT/MERGE operations from the Hibernate StatelessSession.

// insert it
ss.upsert(new Widget(1, "the nema"));
// update it
ss.upsert(new Widget(1, "the name"));

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