java - 外键为空 : Hibernate Spring

Question

我尝试将对象 Run 保存到数据库。我定义了 Run 和 City 之间的关系。一个城市可以有很多次运行。我的 city_id 有问题。一片空白。

Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement] with root cause
java.sql.SQLIntegrityConstraintViolationException: Column 'city_id' cannot be null

我的实体和控制者:城市

@Entity
@Getter
@Setter
@Builder
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "cities")
public class City {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "city_id")
    private long id;
    @OneToMany(mappedBy = "city", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    private List<Run> runs = new ArrayList<>();
    private String name;
}

运行

@Entity
@Builder
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "runs")
public class Run {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    @Column(name = "name_run")
    private String nameRun;
    @Column(name = "distance")
    private double distance;
    @Column(name = "date")
    private Date date;
    @Column(name = "my_time")
    private String myTime;
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "city_id", nullable = false)
    @OnDelete(action = OnDeleteAction.CASCADE)
    @JsonIgnore
    private City city;
}

Controller

@CrossOrigin
@RestController
@RequestMapping("/api/")
public class RunController {

    private RunRepository runRepository;
    private RunService runService;

    public RunController(RunRepository runRepository, RunService runService) {
        this.runRepository = runRepository;
        this.runService = runService;
    }

    @GetMapping("runs")
    public ResponseEntity<List<Run>> getRuns() {
        return runService.getRuns();
    }

    @PostMapping("runs")
    public ResponseEntity addRun(@RequestBody Run run) {

        return new ResponseEntity<>(runRepository.save(run), HttpStatus.OK);
    }
}

我想将运行保存在数据库中。我的测试请求如下所示:

{"nameRun": "测试","距离":"5.0","日期":"2020-12-12","myTime":"50:40",“城市”:“测试1”}

Intelijj 中评估表达式的结果:

为什么城市 = null？这里是映射错误吗？

Answer 1

你可以尝试使用这个 json 但你需要在 json 中传递城市 ID。

{
    "nameRun": "test",
    "distance": "5.0",
    "date": "2020-12-12",
    "myTime": "50:40",
    "city": {
        "id": 1,
        "name": "test1"
    }
}

谢谢