如何在spring boot中保存具有关系的实体

Question

我有一个 Spring Boot 应用程序，我想在其中发送一个具有关系的 json 对象。我有一个名为 meetingSetting 的实体和一个名为 meetingTime 的实体。 MeetingSetting 可以有尽可能多的 meetingTimes，一个 meetingTime 对象属于一个 meetingSetting。但是当我尝试发送它时，我收到以下错误：

not-null property references a null or transient value : com.cbc.coorporateblinddateservice.entities.dates.MeetingTime.meetingsSetting

我尝试调试并注意到在 json 中发送的时间对象中发送时，meetingSetting 为空。有人可以看看我的代码并告诉我我缺少什么，我的猜测是我必须在 meetingSettings 中扩展我的 saveMethod 但这只是一个猜测。

这是我的 MeetingSetting 实体：

@Entity
@Table(name = "meeting_settings")
@Data    
public class MeetingsSetting {

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

    @Column(name = "meeting_name")
    private String meetingName;

    @Column(name = "meeting_url")
    private String meetingUrl;

    @Column(name = "meeting_pw")
    private String meetingPw;

    @OneToMany(mappedBy = "meetingsSetting", cascade = CascadeType.ALL)
    private Set<MeetingTime> meetingTime = new HashSet<>();            
}

meetingTime 实体：

@Entity
@Table(name = "meeting_times")
@Data
public class MeetingTime {

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

    @Column(name = "meeting_date")
    private String date;

    @Column(name = "start_time")
    private String startTime;

    @Column(name = "end_time")
    private String endTime;

    @ManyToOne()
    @JoinColumn(name = "meeting_settings_name", nullable = false)
    private MeetingsSetting meetingsSetting;
}

会议设置控制器：

@RestController
@RequestMapping("/api/meetingSetting")
public class MeetingSettingController {

    @Autowired
    MeetingSettingService meetingSettingService;

    @PostMapping("/")
    public void saveMeeting(@RequestBody MeetingsSetting meetingsSetting){
        meetingSettingService.saveMeeting(meetingsSetting);

    }

服务：

@Service
public class MeetingSettingService {


    @Autowired
    MeetingSettingRepository meetingSettingRepository;


    public void saveMeeting(@RequestBody MeetingsSetting meetingsSetting){
        meetingSettingRepository.save(meetingsSetting);
    }

更新新代码：

会议时间：

    @Entity
@Table(name = "meeting_times")
@Data
public class MeetingTime {

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

    @Column(name = "meeting_date")
    private String date;

    @Column(name = "start_time")
    private String startTime;

    @Column(name = "end_time")
    private String endTime;

    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "meeting_name", nullable = false)
    private MeetingsSetting meetingName;
}

会议设置：

@Entity
@Table(name = "meeting_settings")
@Data

public class MeetingsSetting {

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

    @Column(name = "meeting_name")
    private String meetingName;

    @Column(name = "meeting_url")
    private String meetingUrl;

    @Column(name = "meeting_pw")
    private String meetingPw;

    @OneToMany(mappedBy = "meetingName", cascade = CascadeType.ALL)
    private Set<MeetingTime> meetingTime = new HashSet<>();
}

Sql 脚本：

create table meeting_times
(
    id                  bigint auto_increment
        primary key,
    meeting_date        varchar(255) null,
    start_time          varchar(255) null,
    end_time            varchar(255) null,
    meeting_name varchar(255)       null,
    constraint fk_meeting_times__meeting_settings_name
        foreign key (meeting_name) references meeting_settings (meeting_name)
);

Answer 1

您遇到空问题的原因是在@JoinColumn(name = "meeting_settings_name", nullable = false) 上您有nullable = false。您加入的列是meeting_settings_name，它似乎不是meeting_times 上的列，meeting_settings 上的实际名称是meeting_name。您必须将 meeting_name 添加到 meeting_times 以在两个表之间创建关系才能使其正常工作。