插入@OneToMany关系对象和未在子表中插入父ID的子对象？

Question

I have two model class Gizmo and GizmoChild. I am saving a gizmo object with having gizmoChild object. Gizmo object is saving properly but in the GimoChild table gizmo id is NULL.

Gizmo Model:

  @Entity
  public class Gizmo {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long Id;
    private String field1;
    private String field2;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "gizmo", fetch = 
    FetchType.LAZY)
    private List<GizmoChild> children;
 }

GizmoChild Model:

@Entity 
public class GizmoChild {
 @Id
 @GeneratedValue(strategy = GenerationType.AUTO)
 private Long Id;
 private String childField1;
 private String childField2;
 @ManyToOne
 private Gizmo gizmo;
}

GimoRepository:

@Repository
public interface GizmoRepository extends JpaRepository<Gizmo, Long> {
}

GizmoService:

@Service
public class GizmoService {

@Autowired
 private GizmoRepository gizmoRepository;

 public void save(Gizmo gizmo){
    gizmoRepository.save(gizmo);
}

Controller:

@RequestMapping(value = "/save", method = RequestMethod.POST)
public String saveGizmo(Model model){
    Gizmo gizmo1 = new Gizmo();
    gizmo1.setField1("Field1");
    gizmo1.setField2("Field2");

    GizmoChild gizmoChild = new GizmoChild();
    gizmoChild.setChildField1("ChildField1");
    gizmoChild.setChildField2("ChildField2");

    gizmo1.getChildren().add(gizmoChild);

    gizmoService.save(gizmo1);
    return "redirect:/";
}

I am creating a Gizmo object than i'm creating GizmoChild and adding them on list. Gizmo is saving but GizmoChild table gizmo id is not inserting. How to get rid of this problem?

Answer 1

Firstly you can add GizmoChildRepository too, cause of Gizmo and GizmoChild are different entity object of yours:

@Repository
public interface GizmoChildRepository extends JpaRepository<GizmoChild, Long> {
}

Then changing service method save(Gizmo gizmo) for persisting GizmoChild data too.

GizmoService:

@Service
public class GizmoService {

@Autowired
private GizmoRepository gizmoRepository;

@Autowired
private GizmoChildRepository gizmoChildRepository;

public void save(Gizmo gizmo) {
   for(GizmoChild child : gizmo.getChildren()) {
       gizmoChildRepository.save(child);
   }
   gizmoRepository.save(gizmo);
}

Answer 2

You can try this:

@OneToMany(cascade=CascadeType.ALL, mappedBy="gizmo")
private Set<GizmoChild> workOrders;

@ManyToOne(optional=false)
@JoinColumn(name="gizmo_id", referencedColumnName="id")
private Gizmo gizmo;