Hibernate @OneToOne and ConstraintViolationException on one side of relationship

Question

I'm just testing hibernate @OneToOne relation and validation on entities fields. Here is my one side of relation:

@Table(name = "devices")
@Entity
public class Device extends BaseEntity  {

    @ManyToOne
    @JoinColumn(name = "device_type_id")
    private DeviceTypeEntity deviceType;

    @NotBlank
    private String name;

    @NotBlank
    private String serial;

    @OneToOne(mappedBy = "device",cascade = CascadeType.ALL, fetch=FetchType.EAGER)
    @NotNull
    private Connection connection;

    @OneToMany(cascade = CascadeType.ALL,fetch=FetchType.LAZY)
    @JoinColumn(name="device_id")
    private List<DeviceStatus> deviceStatuses = new ArrayList<DeviceStatus>();

    // getters and setters

}

Other side of relation

@Table(name = "connections")
@Entity
public class Connection extends BaseEntity {

    private static final long serialVersionUID = 1L;

    @Column(name="connection_id", nullable = false)
    @NotBlank
    private String connectionId;

    private String hostname;

    @NotBlank
    private String ip;

    @Column(name="remote_port",nullable = false)
    private Integer remotePort;

    @Column(name="connection_time",nullable = false)
    @Type(type = "com.app.hos.persistance.custom.DateTimeUserType")
    private DateTime connectionTime;

    @Column(name="end_connection_time")
    @Type(type = "com.app.hos.persistance.custom.DateTimeUserType")
    private DateTime endConnectionTime;

    @JsonIgnore
    @OneToOne(fetch=FetchType.EAGER)
    @JoinColumn(name="device_id")
    @NotNull
    private Device device;


    // setters and getters
}

If I set null to 'connectionId' field in Connection class and save 'Device' object with that 'Connection' ie

  connection.setDevice(device);
  device.setConnection(connection);
  deviceRepository.save(device);

I am expecting ConstraintViolationException and it is ok for me. But I have noticed there is a device entity inserted into database. Why? I expect that if expception occure the transaction is rollback and there will be no enitity in database at all (no connection and no device inserted into db).

Answer 1

You set nullable = false in Device Entity.

@OneToOne(mappedBy = "device",cascade = CascadeType.ALL, fetch=FetchType.EAGER)
@JoinColumn(nullable=false)
@NotNull
private Connection connection;

Answer 2

Although what suggested in the other answer fixes the problem from the application point of view, there is a bigger issue here i believe. When you define constraints on application level you mostly do it because you want to detect problems and violations as soon as possible. In this case you wanted to detect a constraint of not null at application level. But the fact that when this constraint wasn't checked, your application wrote data to the database in a case when it shouldn't have, it means you are missing the constraint on database level. This is important and should be handled with bigger priority.