java-保存对象后外键为null

发布时间：2020-12-14 19:27:05 所属栏目：Java 来源：网络整理

导读：我与市民之间有关系： @Entity@Table(name = "citizens")public class Citizen {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private Long id;@Size(max = 10,min = 10,message = "CPR must be exactly 10 characters")private String cpr;@OneT

我与市民之间有关系：

@Entity
@Table(name = "citizens")
public class Citizen {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

@Size(max = 10,min = 10,message = "CPR must be exactly 10 characters")
private String cpr;

@OneToMany(mappedBy = "citizen",cascade = CascadeType.ALL,orphanRemoval = true)
private List<WeeklyCare> weeklyCare;
}

和WeeklyCare：

@Entity
public class WeeklyCare {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "citizen_id")
private Citizen citizen;
}

我有一个REST API,该API接收一个市民列表和一个WeeklyCare列表,并将其保存：

@Autowired
private CitizenRepository citizenRepository;

@CrossOrigin(origins = "http://localhost:4200")
@PostMapping(path = "/add") // Map ONLY GET Requests
@Secured({"ROLE_ADMIN","ROLE_DATAMANAGER"})
public ResponseEntity addNewCitizens(
        @RequestBody List<Citizen> citizens) {
    citizenRepository.saveAll(citizens);
    return new ResponseEntity(new ApiResponse(true,"Filen er blevet indl?st","CITIZENS_SAVED"),HttpStatus.OK);
}

此后,当我查看数据库的weekly_care表时,citizen_id列上的所有行均为null.我想念什么？

最佳答案

这是Hibernate中的常见情况,其原因是未设置关系的倒数：

Citizen c = new Citizen();
WeeklyCare w = new WeeklyCare();
c.getWeeklyCare().add(w);

//The missing link:
w.setCitizen(c);

citizenRepository.save(c);

我不确定如何在您的Web服务请求中配置它…

（编辑：李大同）

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