How do I catch the constraint violation exception from EclipseLink?

I'm using Spring Boot 1.1.9 + EclipseLink 2.5.2. This is the only way I can catch ConstraintViolationException. Note that my handleError(ConstraintViolationException) is a very simple implementation which just returns the first violation it finds.

Note that this code was also required when I switched to Hibernate 4.3.7 and Hibernate Validator 5.1.3.

It seems that adding PersistenceExceptionTranslationPostProcessor exceptionTranslation() to my persistence JavaConfig class also has no effect.

---

import javax.persistence.RollbackException;
import javax.validation.ConstraintViolation;
import javax.validation.ConstraintViolationException;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.transaction.TransactionSystemException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;

@ControllerAdvice
class GlobalExceptionHandler
{
    @ExceptionHandler(TransactionSystemException.class)
    public ResponseEntity<Object> handleError(final TransactionSystemException tse)
    {
        if(tse.getCause() != null && tse.getCause() instanceof RollbackException)
        {
            final RollbackException re = (RollbackException) tse.getCause();

            if(re.getCause() != null && re.getCause() instanceof ConstraintViolationException)
            {
                return handleError((ConstraintViolationException) re.getCause());
            }
        }

        throw tse;
    }


    @ExceptionHandler(ConstraintViolationException.class)
    @SuppressWarnings("unused")
    public ResponseEntity<Object> handleError(final ConstraintViolationException cve)
    {
        for(final ConstraintViolation<?> v : cve.getConstraintViolations())
        {
            return new ResponseEntity<Object>(new Object()
            {
                public String getErrorCode()
                {
                    return "VALIDATION_ERROR";
                }


                public String getMessage()
                {
                    return v.getMessage();
                }
            }, HttpStatus.BAD_REQUEST);
        }

        throw cve;
    }
}

It looks like I won't get any more activity on this question, so I will post my work-around and leave it at that. A number of web searches haven't found much of anything that is helpful. I would have thought this is a textbook case but none of the tutorials I have found covers it.

As it turns out in this condition with EclipseLink, the Exception you can catch when the SQL constraint is violated is the RollBackException that is the result of the em.commit() call. So I have modified my persist method like this:

public void persist(Category category) throws EntityExistsException {
    try {
        utx.begin();
        em.persist(category);
        utx.commit();
    } catch (RollbackException ex) {
        Logger.getLogger(CategoryControl.class.getName()).log(Level.SEVERE, null, ex);
        throw new EntityExistsException(ex);
    } catch (HeuristicMixedException ex) {
        Logger.getLogger(CategoryControl.class.getName()).log(Level.SEVERE, null, ex);
    } catch (HeuristicRollbackException ex) {
        Logger.getLogger(CategoryControl.class.getName()).log(Level.SEVERE, null, ex);
    } catch (SecurityException ex) {
        Logger.getLogger(CategoryControl.class.getName()).log(Level.SEVERE, null, ex);
    } catch (IllegalStateException ex) {
        Logger.getLogger(CategoryControl.class.getName()).log(Level.SEVERE, null, ex);
    } catch (NotSupportedException ex) {
        Logger.getLogger(CategoryControl.class.getName()).log(Level.SEVERE, null, ex);
    } catch (SystemException ex) {
        Logger.getLogger(CategoryControl.class.getName()).log(Level.SEVERE, null, ex);
    }
}

So the caller catches the EntityExistsException and takes the appropriate action. The log still fills up with the internal exceptions but that can be shut off later.

I realize that this is a bit of an abuse of the intent of the EntityExistsException that is normally only used when an entity ID field is re-used, but for the purposes of the user application it doesn't matter.

If anyone has a better approach please post a new answer or comment.

EclipseLink should only be throwing either a PersitenceException or a RollbackException depending on the environment and the order of operations you are calling on the EntityManager. What is your logging level? It is likely that you are seeing these exceptions logged by EclipseLink but only thrown as causes of the RollbackException.

You can turn off exception logging with the PU property but for diagnostic purposes it is generally better to allow EclipseLink to log the exceptions.

Edit your persistence.xml adding the following property:

property name="eclipselink.exception-handler" value="your.own.package.path.YourOwnExceptionHandler"

Now create the class YourOwnExceptionHandler (on the correct package). It requires to implement org.eclipse.persistence.exceptions.ExceptionHandler.

Create a non argument constructor and the required method handleException(...).

Inside this method, you can catch the exceptions!