how to handle org.hibernate.exception.ConstraintViolationException, I using try catch doesn't work

Question

How to handle org.hibernate.exception.ConstraintViolationException? I am using try-catch, but it doesn't work:

try {
    CandidateCollege newCandidateCollege = candidateCollegeRepo.save(candidateCollege);
    System.out.println(newCandidateCollege);
    if(newCandidateCollege != null){
        return new WithIncludes<>(newCandidateCollege);
    }
} catch (Exception ex) {
    System.out.println("==========ex.getMessage()============");
    log.error(ex.getMessage());
}
return null;

Exception:

2017-05-25 15:52:43 ERROR SqlExceptionHelper:131 - Duplicate entry '270-1-4-2' for key 'ux_candidate_college'
==========ex.getMessage()============
2017-05-25 15:52:43 ERROR CandidateCollegeServiceImpl:67 - could not execute statement; SQL [n/a]; constraint [ux_candidate_college]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement

Well, don't try saving a duplicate entry. And if you really want to catch that exception, read its stack trace: you'll see that it happens at flush time, not when calling save(), because flush is when Hibernate actually executes the inserts and updates. So, call flush explicitely inside your try block, or put the try block at a higher level, outside of the transaction. — JB Nizet
– JB Nizet, Commented May 25, 2017 at 8:07

Shafin Mahmud · Accepted Answer · 2017-05-25 08:23:16Z

6

It wont catch your Exception because the ConstraintViolationException is being thrown at the time of transaction flush which is actually not happening between your try-catch block or during save() call.

you can surround the try-catch at some higher level like eg. in the Controller and you could check for the ConstraintViolationException is thrown and take action on accord.

or can flush your transaction explicitly after save()

answered May 25, 2017 at 8:23

Shafin Mahmud

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3 Comments

Green Baylee Over a year ago

Thanks , very helpful!

Govind Kumar Thakur Over a year ago

Hi @GreenBaylee I am also facing something similar. And my try catch is not able to handle the exception as method is annotated with Transactional. Could you please tell me the approach you used to fix this problem if you remember. Thanks in advance.

Shafin Mahmud Over a year ago

@Govind Use try catch where you are calling your transactional method.

Martijn van der Woud · Accepted Answer · 2017-05-25 08:10:06Z

0

Looking at the output, I would say that the catch block is executed. Note the ===== in the output. The message above that is just Hibernate's internal logging. I would expect that you method does indeed return null. Have you checked that?

answered May 25, 2017 at 8:10

Martijn van der Woud

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robot_alien · Accepted Answer · 2017-05-25 08:13:36Z

0

Before saving that entry in the db, you can check if it already exists or not, if not then you can go with saving the entry. Also specify
catch(ConstraintViolationException cve){ //some appropriate thing to deal with the exception }

this way you also get to handle the specific exception case that you are looking for!

edited May 25, 2017 at 8:13

answered May 25, 2017 at 8:08

robot_alien

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1 Comment

Shafin Mahmud Over a year ago

May be it wouldnt be a better idea to check the existence before saving cause it will cost another round trip to the database. Handling exception at correct point would be performance healthy @coolgirl

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