How to handle a PSQLException in java?

Question

I have a unique constraint on one of my entities and whenever I get a PSQLException which occurs whenever that constraint is violated, I want to respond with a bad request. This is my exception handler which I tried to implement: ``` @ControllerAdvice public class DatabaseExceptionHandler { @ExceptionHandler(value = PSQLException.class) @ResponseStatus(HttpStatus.BAD_REQUEST) public void handleDatabaseExceptions(PSQLException e) { // i want to respond with a bad request only when this condition is satisfied // // if (e.getSQLState().equals("23505")) { // // } } } ``` And this is where the model is saved in db: ``` public DepartmentForHoliday setDepartment(DepartmentForHoliday department) { if (department.getDepartmentId() == null) { Department savedDepartment = new Department(); savedDepartment.setName(department.getName()); try { departmentRepository.save(savedDepartment); } catch (PSQLException e) { /*here i have a compiler error which says that this exception is never thrown in the…

Accepted Answer

Key problem is that `PSQLException` is wrapped into some Spring exception (which I assume from your code); you have to unwrap it (for example using guava's `Throwables`):

```
public DepartmentForHoliday setDepartment(DepartmentForHoliday department) {
    if (department.getDepartmentId() == null) {
        Department savedDepartment = new Department();
        savedDepartment.setName(department.getName());
        try {
            departmentRepository.save(savedDepartment);
        } catch (RuntimeException e) {
            Throwable rootCause = com.google.common.base.Throwables.getRootCause(e);
            if (rootCause instanceof SQLException) {
                if ("23505".equals(((SQLException) rootCause).getSQLState())) {
                    // do smth interesting :)
                }
            }
        }
    }
}
```

Once you do that you can throw your custom exception and handle it in `DatabaseExceptionHandler`

How to handle a PSQLException in java?

Solution

Problem