I have stepped through the code and when the EntityManager throws an
exception due to an SQL issue, in my case a uniqueness constraint, the
EJBException is thrown to the first class that is outside of the
container managed transaction's control. I would like to catch the SQL
Exception, or it's equivalent, and throw a meaningful application
exception. I do not want to clutter my Model tier throwing
EJBExceptions to the Client tier.
Thanks
-----Original Message-----
From: Mahesh.Kannan_at_Sun.COM [mailto:Mahesh.Kannan_at_Sun.COM]
Sent: Monday, October 02, 2006 2:36 PM
To: ejb_at_glassfish.dev.java.net
Cc: persistence_at_glassfish.dev.java.net
Subject: Re: EJB 3 and JPA Exception Handling
CCing persistnce team.
Butash, Bob wrote:
> All,
>
> I have a question regarding Exception Handling regarding JPA code.
>
> Here is my Scenario:
>
> I have a JSF backing bean that is invoking a business service via a
> JNDI lookup through the service locator pattern.
>
> public String registerNewUser() throws SystemUserException,
> Exception
> {
> SystemUser user = (SystemUser)getManagedBeanValue("user")
> obtainSystemUserService().addSystemUser(user);
> user.setPassword(null);
>
> UserState userState =
> (UserState)getManagedBeanValue("userState");
> userState.setUser(retrieveSystemUser());
> userState.setLoggedIn(true);
> return "success";
> }
>
> I have a Local Stateless Session Bean that is acting as a Business
> Service. The saveObject method is annotated to require a transaction.
> It delegates to another Local Stateless Session bean that is acting as
> the DAO. It merely throws any application exceptions that are thrown
> from the DAO.
>
> @TransactionAttribute(TransactionAttributeType.SUPPORTED)
> public Object addSystemUser(SystemUser user) throws
> SystemUserServiceException
> {
> return getSystemUserDAO().persistEntity(user);
> }
>
>
> The Local DAO Stateless Session Bean's method annotated to require a
> transaction. This method is invoking the EntityManager to perform the
> persist. The call to the persist is surrounded with a try catch to
> attempt to catch an exception during the persist and wrap it in an
> Application exception.
>
> @TransactionAttribute(TransactionAttributeType.REQUIRED)
> public SystemUser persistEntity(SystemUser entity)
> {
> try
> {
> return (SystemUser)super.persistEntity(entity);
> }
> catch(Exception e)
> {
> throw new SystemUserException("Duplicate user");
> }
> }
>
>
> However, if there is an error the catch is not hit and no exception
> processing is encountered until the stack is back at the POJO JSF
> backing bean and at that point I am catching an EJBException.
>
You may add a System.out.println() in your catch (Exception e) block to
be sure that you got an exception. May be you are getting the exception
when the Tx completes.
> I have tried placing try catches at the Business Service Tier as well
> as I have an EJB interceptor that is wrapping the call to the
> context.proceed with a try/catch. The only time I can actually catch
> the EJBException is when I'm out of the transactional processing,
> which is the POJO backing bean. I have noticed if I change the
> transactional control on the Business Service method to be
> NOT_SUPPORTED I can catch the exception at that point, but that means
> if this was part of a more complex tranasaction all of my
> transactional control would be lost.
>
> Is there a way to catch Exceptions thrown from the
> EntityManager.persist() and wrap them in a meaningful
> ApplicationException?
>
> Thanks for your assistance
>
> Bob Butash
>
>
>
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