Handle Hibernate optimistic locking with Spring - spring

Question

I am using Hibernate and Spring Data, it will perform optimistic locking when insert or update an entity, and if the version in database doesn't match with the one to persist, it will throw exception StaleObjectStateException, in Spring, you need to catch it with ObjectOptimisticLockingFailureException.
What I want to do is catch the exception and ask the user to refresh the page in order to get the latest data from database like below:
public void cancelRequest()
{
try
{
request.setStatus(StatusEnum.CANCELLED);
this.request = topUpRequestService.insertOrUpdate(request);
loadRequests();
//perform other tasks...
} catch (ObjectOptimisticLockingFailureException ex)
{
FacesUtils.showErrorMessage(null, "Action Failed.", FacesUtils.getMessage("message.pleaseReload"));
}
}
I assume it will also work with the code below but I have not tested it yet.
public void cancelRequest()
{
RequestModel latestModel = requestService.findOne(request.getId());
if(latestModel.getVersion() != request.getVersion())
{
FacesUtils.showErrorMessage(null, "Action Failed.", FacesUtils.getMessage("message.pleaseReload"));
}
else
{
request.setStatus(StatusEnum.CANCELLED);
this.request = requestService.insertOrUpdate(request);
loadRequests();
//perform other tasks...
}
}
I need to apply this checking on everywhere I call requestService.insertOrUpdate(request); and I don't want to apply them one by one. Therefore, I decide to place the checking code inside the function insertOrUpdate(entity) itself.
#Transactional
public abstract class BaseServiceImpl<M extends Serializable, ID extends Serializable, R extends JpaRepository<M, ID>>
implements BaseService<M, ID, R>
{
protected R repository;
protected ID id;
#Override
public synchronized M insertOrUpdate(M entity)
{
try
{
return repository.save(entity);
} catch (ObjectOptimisticLockingFailureException ex)
{
FacesUtils.showErrorMessage(null, FacesUtils.getMessage("message.actionFailed"),
FacesUtils.getMessage("message.pleaseReload"));
return entity;
}
}
}
My main question is, there will be one problem with this approach. The caller side will not know whether the entity persisted successfully or not since the exception will be caught and handled inside the function, so the caller side will always assume the persist was success, and continue do the other tasks, which is I don't want. I want it to stop performing tasks if fail to persist:
public void cancelRequest()
{
try
{
request.setStatus(StatusEnum.CANCELLED);
this.request = topUpRequestService.insertOrUpdate(request);
//I want it to stop here if fail to persist, don't load the requests and perform other tasks.
loadRequests();
//perform other tasks...
} catch (ObjectOptimisticLockingFailureException ex)
{
FacesUtils.showErrorMessage(null, "Action Failed.", FacesUtils.getMessage("message.pleaseReload"));
}
}
I know when calling the insertOrUpdate , I can catch the returned entiry by declaring new model variable, and compare it's version to the original one, if version is same, means the persistance was failed. But if I doing it this way, I have to write the version checking code on everywhere I call insertOrUpdate. Any better approach then this?

Answer 1

The closest way to being able to do this and not having to necessarily make significant code changes at all the invocation points would be to look into some type of Spring AOP advice that works similar to Spring's #Transactional annotation.
#FacesReloadOnException( ObjectOptimisticLockingFailureException.class )
public void theRequestHandlerMethod() {
// call your service here
}
The idea is that the #FacesReloadOnException annotation triggers an around advice that catches any exception provided in the annotation value and does basically handles the call the FacesUtils should any of those exception classes be thrown.
The other options you have available aren't going to be nearly as straight forward and will require that you touch all your usage points in some fashion, its just inevitable.
But I certainly would not consider putting the try/catch block in the service tier if you don't want to alter your service tier's method return types because the controllers are going to need more context as you've pointed out. The only way to push that try/catch block downstream would be if you returned some type of Result object that your controller could then inspect like
public void someControllerRequestMethod() {
InsertOrUpdateResult result = yourService.insertOrUpdate( theObject );
if ( result.isSuccess() ) {
loadRequests();
}
else {
FacesUtils.showErrorMessage( ... );
}
}
Otherwise you'd need to get creative if you want to somehow centralize this in your web tier. Perhaps a web tier utility class that mimics your BaseService interface like the following:
public <T extends BaseService, U> U insertOrUpdate(T service, U object, Consumer<U> f) {
try {
U result = service.insertOrUpdate( object );
f.accept( result );
return result;
}
catch ( ObjectOptimisticLockingFailureException e ) {
FacesUtils.showErrorMessage( ... );
}
}
But being frank, unless you have a lot of call sites that are similar enough to where such a generalization with a consumer like this makes sense, you may find its more effort and work to generalize it than it would to just place the try/catch block in the controller itself.