JpaRepository not updating entity

abarazal :

As far as I undestood, JpaRepository save() method should update my entity in database.

I have a table in MySQL called REF_PERIOD with two columns only: code_id, which is INT and Primary Key, and code_name, which is VARCHAR.

This is my Entity:

@Data
@Entity
@Table(name = "REF_PERIOD")
public class PayRefPeriod {

    @Id
    @Column(name = "code_id")
    private int codeId;

    @Column(name = "code_name", length = 254, nullable = false)
    private String codeName;
}

My Repository:

@Repository
public interface PayRefPeriodRepository extends JpaRepository<PayRefPeriod, Integer> {

}

And the Controller:

@Slf4j
@RestController
@RequestMapping("/api")
public class PayRefPeriodController {

    @Autowired
    private PayRefPeriodRepository payRefPeriodRepository;

    // Get all pay reference periods
    @GetMapping("/payrefperiods")
    public List<PayRefPeriod> getAllPayRefPeriod() {
        return payRefPeriodRepository.findAll();
    }

    // Create a new pay reference period
    @PostMapping("/payrefperiods")
    public PayRefPeriod createPayRefPeriod(@Valid @RequestBody PayRefPeriod payRefPeriod) {
        return payRefPeriodRepository.save(payRefPeriod);
    }

    // Get a single pay reference period
    @GetMapping("/payrefperiods/{id}")
    public PayRefPeriod PayRefPeriod(@PathVariable(value = "id") int payRefPeriodId) {
        return payRefPeriodRepository.findById(payRefPeriodId)
                .orElseThrow(() -> new ResourceNotFoundException("PayRefPeriod", "id", payRefPeriodId));
    }

    // Update a pay reference period
    @PutMapping("/payrefperiods/{id}")
    public PayRefPeriod updatePayRefPeriod(@PathVariable(value = "id") int payRefPeriodId,
                                      @Valid @RequestBody PayRefPeriod payRefPeriodDetails) {

        PayRefPeriod payRefPeriod = payRefPeriodRepository.findById(payRefPeriodId)
                .orElseThrow(() -> new ResourceNotFoundException("PayRefPeriod", "id", payRefPeriodId));

        payRefPeriod.setCodeName(payRefPeriodDetails.getCodeName());

        log.debug(payRefPeriod.toString());

        return payRefPeriodRepository.save(payRefPeriod);
    }

    // Delete a pay reference period
    @DeleteMapping("/payrefperiods/{id}")
    public ResponseEntity<?> deletePayRefPeriod(@PathVariable(value = "id") int payRefPeriodId) {
        PayRefPeriod payRefPeriod = payRefPeriodRepository.findById(payRefPeriodId)
                .orElseThrow(() -> new ResourceNotFoundException("PayRefPeriod", "id", payRefPeriodId));

        payRefPeriodRepository.delete(payRefPeriod);

        return ResponseEntity.ok().build();
    }
}

I expect the updatePayRefPeriod method to update my entity (which has Id 0 in MySQL database), however it throws an exception: java.sql.SQLIntegrityConstraintViolationException: Duplicate entry '0' for key 'PRIMARY'.

What I'm doing wrong?

Yavuz Tas :

I suppose it might be a mysql driver specific limitation that for java primitive type int when we use it for identifier. I suggest you change the type of the codeId to its boxed object type Integer.

@Id
@Column(name = "code_id")
private Integer codeId;

Thus the underlying hibernate can understand the difference between a null identifier and not null but 0 valued identifier when it generates the corresponding update queries.