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How can I tell if current session is dirty?

I want to publish an event if and only if there were changes to the DB. I'm running under #Transaction is Spring context and I come up with this check:
Session session = entityManager.unwrap(Session.class);
session.isDirty();
That seems to fail for new (Transient) objects:
#Transactional
public Entity save(Entity newEntity) {
Entity entity = entityRepository.save(newEntity);
Session session = entityManager.unwrap(Session.class);
session.isDirty(); // <-- returns `false` ):
return entity;
}
Based on the answer here https://stackoverflow.com/a/5268617/672689 I would expect it to work and return true.
What am I missing?
UPDATE
Considering #fladdimir answer, although this function is called in a transaction context, I did add the #Transactional (from org.springframework.transaction.annotation) on the function. but I still encounter the same behaviour. The isDirty is returning false.
Moreover, as expected, the new entity doesn't shows on the DB while the program is hold on breakpoint at the line of the session.isDirty().
UPDATE_2
I also tried to change the session flush modes before calling the repo save, also without any effect:
session.setFlushMode(FlushModeType.COMMIT);
session.setHibernateFlushMode(FlushMode.MANUAL);

First of all, Session.isDirty() has a different meaning than what I understood. It tells if the current session is holding in memory queries which still haven't been sent to the DB. While I thought it tells if the transaction have changing queries. When saving a new entity, even in transaction, the insert query must be sent to the DB in order to get the new entity id, therefore the isDirty() will always be false after it.
So I ended up creating a class to extend SessionImpl and hold the change status for the session, updating it on persist and merge calls (the functions hibernate is using)
So this is the class I wrote:
import org.hibernate.HibernateException;
import org.hibernate.internal.SessionCreationOptions;
import org.hibernate.internal.SessionFactoryImpl;
import org.hibernate.internal.SessionImpl;
public class CustomSession extends SessionImpl {
private boolean changed;
public CustomSession(SessionFactoryImpl factory, SessionCreationOptions options) {
super(factory, options);
changed = false;
}
#Override
public void persist(Object object) throws HibernateException {
super.persist(object);
changed = true;
}
#Override
public void flush() throws HibernateException {
changed = changed || isDirty();
super.flush();
}
public boolean isChanged() {
return changed || isDirty();
}
}
In order to use it I had to:
extend SessionFactoryImpl.SessionBuilderImpl to override the openSession function and return my CustomSession
extend SessionFactoryImpl to override the withOptions function to return the extended SessionFactoryImpl.SessionBuilderImpl
extend AbstractDelegatingSessionFactoryBuilderImplementor to override the build function to return the extended SessionFactoryImpl
implement SessionFactoryBuilderFactory to implement getSessionFactoryBuilder to return the extended AbstractDelegatingSessionFactoryBuilderImplementor
add org.hibernate.boot.spi.SessionFactoryBuilderFactory file under META-INF/services with value of my SessionFactoryBuilderFactory implementation full class name (for the spring to be aware of it).
UPDATE
There was a bug with capturing the "merge" calls (as tremendous7 comment), so I end up capturing the isDirty state before any flush, and also checking it once more when checking isChanged()

The following is a different way you might be able to leverage to track dirtiness.
Though architecturally different than your sample code, it may be more to the point of your actual goal (I want to publish an event if and only if there were changes to the DB).
Maybe you could use an Interceptor listener to let the entity manager do the heavy lifting and just TELL you what's dirty. Then you only have to react to it, instead of prod it to sort out what's dirty in the first place.
Take a look at this article: https://www.baeldung.com/hibernate-entity-lifecycle
It has a lot of test cases that basically check for dirtiness of objects being saved in various contexts and then it relies on a piece of code called the DirtyDataInspector that effectively listens to any items that are flagged dirty on flush and then just remembers them (i.e. keeps them in a list) so the unit test cases can assert that the things that SHOULD have been dirty were actually flushed as dirty.
The dirty data inspector code is on their github. Here's the direct link for ease of access.
Here is the code where the interceptor is applied to the factory so it can be effective. You might need to write this up in your injection framework accordingly.
The code for the Interceptor it is based on has a TON of lifecycle methods you can probably exploit to get the perfect behavior for "do this if there was actually a dirty save that occured".
You can see the full docs of it here.

We do not know your complete setup, but as #Christian Beikov suggested in the comment, is it possible that the insertion was already flushed before you call isDirty()?
This would happen when you called repository.save(newEntity) without a running transaction, since the SimpleJpaRepository's save method is annotated itself with #Transactional:
#Transactional
#Override
public <S extends T> S save(S entity) {
...
}
This will wrap the call in a new transaction if none is already active, and flush the insertion to the DB at the end of the transaction just before the method returns.
You might choose to annotate the method where you call save and isDirty with #Transactional, so that the transaction is created when your method is called, and propagated to the repository call. This way the transaction would not be committed when the save returns, and the session would still be dirty.
(edit, just for completeness: in case of using an identity ID generation strategy, the insertion of newly created entity is flushed during a repository's save call to generate the ID, before the running transaction is committed)

using spring transactionManager with Hibernate after transaction committed only one repository of two is actually being committed

I have a #Transactional method that changes the state of two entities of different, not related, repositories.
something like this:
#Transactional
public void foo() {
A a = repoA.findById(1);
a.setState(s1);
B b = repoB.findById(1);
b.setState(s2);
// (and I also do repoA.save(a); and repoB.save(b); although it is redundant)
}
I also have a transactional method bar that calls foo and publishes an event that is being caught by a TransactionalEventListener like this:
#Transactional
public void bar() {
foo();
applicationEventPublisher.publishEvent(new AppEvent(123));
}
and
#Component
public class MyApplicationEventListener {
#TransactionalEventListener
public void handleAfterCommit(AppEvent appEvent){
//do something;
}
}
Now the issue is that in 80% of the time when handleAfterCommit method is invoked, only (A a ) is being committed but (B b) is losing its changes.
I need help to understand what is going on here, I tried to debug and explore the
TransactionAspectSupport.currentTransactionStatus() but didn't find any insights.
Thanks,
Eilon

I found the issue, we are using a custom AttributeConverter and we didnt implement Equals for the relevant javav object, this caused every dirty check on select to fail and do a full update (overriding values that meanwhile have been changed)
Thanks

transactional method throwing "no transactional entityManager available"

I have a method that is defined as #transactional. In fact I have a method calling a method that calls a method and all three are #transactional. The transactional logic worked fine, until I pulled a few methods out into an abstract class for some code reuse, which appears to have broken my logic somehow.
The transactional method is from an abstract class, here is a partial snippet of the relevant parts (I have to rewrite this by hand so forgive me for typos):
public abstract class ReadWriteService<ReadEntityTempalte extends IEntity, WriteEntityTemplate extends IEntity>
//extends jpaRepository, created using #enableJpaRepositories
private searchRepository<WriteEntityTemplate, String> writeRepository;
#PersistenceContext
private EntityManager em;
#transactional
public ReadEntityTemplate save(final WriteEntityTemplate entity){
if(entity == null) return null;
WriteEntityTemplate returnValue = writeRepository_.save(entity);
postSave(returnValue); //checks our security logic
flush();
ReadEntityTemplate returnEntity = find(returnValue.getId());
//required to detect changes made to the view by our save
em.refresh(returnEntity);
}
It's written this way because we are using views so the return value may be modified in the find() to the view. This logic worked in the past, and still works for a number of calls.
The method that fails is:
#Override
#transational
public void configure(EntityFileConfig config) throws ClassNotFoundException{
//load config from file
for(EntityConfig entityConfig: entityConfigs){
EntityType entityType=EntityTypeService_.find(entityConfig.getKey());
if(entityType==null){
entityType = EntityType.createByRequiredFields(entityConfig.getKey());
}
//update entityType to reflect config file.
entityType = entityTypeService_.save(entityType);
for(String permissionName: entityConfig.getPermissions()){
if(!entityTypeService_.hasPermission(entityType, permissionName)){
Permission permission = permissionSetup.getPermission(permissionName);
if(permission!=null)
//fails on below lines
permissionService._.addPermission(entityType, permission);
}
}
}
}
both the entityTypeService and the permissionService extend the above abstract class and use the same save method without alteration, addPermissions is a forloop that calls save on each permission.
The entityTypeService works, but the permissionService fails. When The permission service is called if I do em.isTransactionalEntity it returns false.
All #transactional annotations are using the spring annotation, not the javax one.
Actually, it seems as if a few of the permissions would save and others wouldn't, almost as if it's non-deterministic, but this may simple be due to modifying a database file that had some of the values already set and thus didn't need to run some of the logic the first time through.
I've done quite a bit of stumbling around but am no closer to determining what would cause my transaction to end. I had thought perhaps it was the #persistenceContext, since the JPARepos get their entityManager through a different approach then autowireing with #persistenceContext, but if that were the case everything would fail?
Any help would be appreciated, I'm pretty stumped on the cause of this.

Assuming you have enabled #EnableTransactionManagement on #Configuration class.
Since you didn't set any propagation on #Transaction the default value is Required. It means all methods must be part of transaction. Since one of your abstract methods is not part of the #Transactional hence the error.
For more information on Spring Transactions.
Note: Image taken from above link.

Spring Transaction Annotations - get active transaction

In my Spring application I have service-layer methods marked as #Transactional(propagation=Propagation.REQUIRED) and am using <tx:annotation-driven />. Normally the default behavior of automatically committing the transaction when the method completes works like a charm. But in the particular case, I need to commit shortly before the end of the method - yes, even if the parts that come after that point throw an exception.
Is there a way inside such a method to get access to the current transaction? I tried this:
TransactionDefinition td = new DefaultTransactionDefinition(TransactionDefinition.PROPAGATION_MANDATORY); // make sure we're talking about the same transaction already provided by the annotation
TransactionStatus status = transactionManager.getTransaction(td);
// perform various JDBC operations
transactionManager.commit(status);
methodThatNeedsToBeCalledAfterCommit();
But looking through my logs, I only see "AbstractPlatformTransactionManager.processCommit(752) | Initiating transaction commit" occurring once, and from the timestamps this appears to be after methodThatNeedsToBeCalledAfterCommit(), which would be the normal behavior for #Transactional methods.
Is there a way to actually force a commit inside such a method?

I don't think so. Moreover, Spring will try to recommit at the end of your method.
So 2 commits : bad.
You should rethink the organization of your methods.
Maybe divide the existing one in 2 methods : one with #Trnasactional, the other with your remaining lines.

This is probably because the default transaction propagation is PROPAGATION_REQUIRED, and so will commit only when the entire transaction is completed - which is the outer method for you. You can try with PROPAGATION_REQUIRES_NEW:
td.setPropagationBehavior(TransactionDefinition.PROPAGATION_REQUIRED);
Another alternative would be to use TransactionTemplate

Try this call this method from the program where you want to apply transaction.
DefaultTransactionDefinition transdefinition = new DefaultTransactionDefinition();
PlatformTransactionManager manager =new PlatformTransactionManager();
TransactionStatus status=null;
public void beginTransaction()
{
transdefinition.setPropagationBehavior(0);
status = manager.getTransaction(transdefinition);
}
public void commitTransaction()
{
if(status.isCompleted()){
manager.commit(status);
}
}
public void rollbackTransaction()
{
if(!status.isCompleted()){
manager.rollback(status);
}
}

REQUIRES_NEW within REQUIRES_NEW within REQUIRES_NEW ... on and on

JBoss 4.x
EJB 3.0
I've seen code like the following (greatly abbreviated):
#Stateless
#TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
public class EJB1 implements IEJB1
{
#EJB
private IEJB1 self;
#EJB
private IEJB2 ejb2;
#TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
public boolean someMethod1()
{
return someMethod2();
}
#TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
public boolean someMethod2()
{
return self.someMethod3();
}
#TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
public boolean someMethod3()
{
return ejb2.someMethod1();
}
}
And say EJB2 is almost an exact copy of EJB1 (same three methods), and EJB2.someMethod3() calls into EJB3.someMethod1(), which then finally in EJB3.someMethod3() writes to the DB.
This is a contrived example, but have seen similar code to the above in our codebase. The code actually works just fine.
However, it feels like terrible practice and I'm concerned about the #TransactionAttribute(TransactionAttributeType.REQUIRES_NEW) on every method that doesn't even actually perform any DB writes. Does this actually create a new transaction every single time for every method call with the result of:
new transaction
-new transaction
--new transaction
---new transaction
...(many more)
-------new transaciton (DB write)
And then unwraps at that point? Would this ever be a cause for performance concern? Additional thoughts?

Does this actually create a new transaction every single time for
every method call
No, it doesn't. The new transaction will be created only when calling method by EJB reference from another bean. Invoking method2 from method1 within the same bean won't spawn the new transaction.
See also here and here. The latter is exceptionally good article, explaining transaction management in EJB.
Edit:
Thanks #korifey for pointing out, that method2 actually calls method3 on bean reference, thus resulting in a new transaction.

It really creates new JTA transaction in every EJB and this must do a serious performance effect to read-only methods (which makes only SELECTS, not updates). Use #SUPPORTS for read-only methods