why org.hibernate.dialect.PostgreSQLDialect cannot be cast to org.hibernate.dialect.Dialect?

Question

In hibernate.xml, I have :

<property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>

and here is what I'm trying to do:

final Session sess = sessionFactory.openSession();
Transaction tx = null;
try {
    tx = sess.beginTransaction();
    Collection<Rfc> rfcs;
    Criteria criteria = sessionFactory.getCurrentSession().createCriteria(Rfc.class);
    criteria = criteria.add(Restrictions.like(Rfc.RFC_IDENTIFIER, input.replace('*', '%')));
    rfcs = criteria.list();
    // ...
    tx.commit();
} catch (final Exception e) {
    if (tx != null) {
        tx.rollback();
    }
    throw new IllegalArgumentException(e);
} finally {
    sess.close();
}

This all seems very straightforward, but I'm getting:

Caused by: java.lang.ClassCastException: org.hibernate.dialect.PostgreSQLDialect cannot be cast to org.hibernate.dialect.Dialect at org.hibernate.service.jdbc.dialect.internal.

Here is the relevant bit of my pom.xml:

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <!--            <version>4.1.9.Final</version>-->
        <version>4.1.0.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>3.6.3.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-annotations</artifactId>
        <version>3.5.6-Final</version>
    </dependency>

I've traced the issue to a method of org.hibernate.service.jdbc.dialect.internal.DialectFactoryImpl.constructDialect(), where we find:

private Dialect constructDialect(String dialectName) {
    try {
        return ( Dialect ) classLoaderService.classForName( dialectName ).newInstance();
    }
    catch ( ClassLoadingException e ) {
        throw new HibernateException( "Dialect class not found: " + dialectName, e );
    }
    catch ( HibernateException e ) {
        throw e;
    }
    catch ( Exception e ) {
        throw new HibernateException( "Could not instantiate dialect class", e );
    }
}

Attempting to instantiate a Dialog here results in the above ClassCastException.

Just to be extra sure I have the right class, I displayed all the superclasses in its hierarchy... and here is exactly what I see in my console:

class org.hibernate.dialect.PostgreSQLDialect

class org.hibernate.dialect.PostgreSQL82Dialect

class org.hibernate.dialect.PostgreSQL81Dialect

class org.hibernate.dialect.Dialect

yet... sure enough, org.hibernate.dialect.Dialect.class.isAssignableFrom(classLoaderService.classForName( dialectName ) ) returns false.

Could this be some sort of incompatibility between versions of hibernate and the drivers provided by Postgresql?

Been tearing my hair out. Any help much appreciated!

Answer 1

Yep. The problem, it seems, was that I was trying to mix incompatible versions of various hibernate dependencies. I just replaced section of the pom.xml cited above with :

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-search</artifactId>
        <version>4.3.0.Final</version>
    </dependency>

And I'm on to my next issue!

Answer 2

That was a Hibernate known bug that has been fixed in 4.1.4.Final

Hibernate bug report: https://hibernate.atlassian.net/browse/HHH-7084