[hibernate-issues] [Hibernate-JIRA] Created: (HHH-5550) Hibernate.createBlob() fails when used in current_session_context_class=thread mode

[Zemian Deng (JIRA)]

Hibernate.createBlob() fails when used in current_session_context_class=thread mode
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                 Key: HHH-5550
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5550
             Project: Hibernate Core
          Issue Type: Bug
    Affects Versions: 3.5.5
            Reporter: Zemian Deng


See https://forum.hibernate.org/viewtopic.php?f=1&t=1004366

Here is a unit test failed case:
{code:java}
package deng.hibernate.examples.blob;

import org.hibernate.*;
import org.hibernate.cfg.*;
import org.junit.Test;

public class HibernateCreateBlobFailedCase {
		
	@Test
	public void createBlob() {
		Configuration cfg = new Configuration();
		SessionFactory sessionFactory = cfg.configure().buildSessionFactory();
		Session session = sessionFactory.getCurrentSession();
		Transaction tx = null;
		try {
			tx = session.beginTransaction();
			byte[] blobBytes = new byte[]{};
			Hibernate.createBlob(blobBytes, session);
		} catch (Throwable e) {
			tx.rollback();
			throw new RuntimeException(e);
		} finally {
			sessionFactory.close();
		}
	}
	
}
{code}

Set hibernate.cfg.xml with thread session context
{code:xml}
...
<property name="current_session_context_class">thread</property>
...
{code}

You will get this stack trace
{noformat}
java.lang.RuntimeException: java.lang.ClassCastException: $Proxy4 cannot be cast to org.hibernate.engine.jdbc.LobCreationContext
	at deng.hibernate.examples.blob.HibernateCreateBlobFailedCase.createBlob(HibernateCreateBlobFailedCase.java:24)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:49)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.lang.ClassCastException: $Proxy4 cannot be cast to org.hibernate.engine.jdbc.LobCreationContext
	at org.hibernate.Hibernate.getLobCreator(Hibernate.java:502)
	at org.hibernate.Hibernate.getLobCreator(Hibernate.java:498)
	at org.hibernate.Hibernate.createBlob(Hibernate.java:494)
	at deng.hibernate.examples.blob.HibernateCreateBlobFailedCase.createBlob(HibernateCreateBlobFailedCase.java:21)
	... 22 more
{noformat}

As described in forum, this problem occurred because the session object we get using {{sessionFactory.getCurrentSession();}} is an wrapped ThreadLocalSessionContext instance that can not be cast into LobCreationContext. There is no easy way to unwrap and get the original session object, to pass to createBlob method.

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