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从POST / GET请求返回到Spring Boot应用的JSON对象中外键的空值

分类：编程问答

如何解决从POST / GET请求返回到Spring Boot应用的JSON对象中外键的空值

竞技场的好人！

我遇到了问题，希望您能向我解释我的代码的问题所在。 构建Spring Boot应用程序：对于这个开发阶段，一切都很好，除了我没有从HTTP获取请求的事实之外，这些都是我数据库中现有外键的字段值。我在Google和StackOverflow上度过了一天，没有发现任何提示。

我使用Entity-DTO-ResponceModel--RequestModel模式将数据从有效负载传输到数据库，再传输回数据库。 我使用modelmapper.class进行类之间的映射。 在ServiceImplementation类中执行的所有业务逻辑。

因此，我的实体之间存在多对一关系，这里有一个小问题。通过请求后，我创建了一个新用户，同时创建了用户的私有Group和Event（在UserServiceImpl.class中进行了此操作）。

立即在数据库中创建的所有内容都没有问题。然后，我得到了该新用户的对象，对其进行了转换，并作为响应发送回了前端。所以我有了JSON对象，并在Postman中看到了它。所有字段均已到位，但缺少数据库中存在的几个值，并替换为null。

具体来说-我在此JSOn对象中获取了“ author_id”，“ admin_id”和“ group_id”的空值

{
"publicUserId": "FgKP0BTGqI94nEY","name": "Alex","phone": "222222","email": "333@gmail.com","userMoto": "Go-go forward","usersTodos": null,"usersEvents": [
    {
        "publicEventId": "zRmVNyS9A32OWPW","nameEvent": "Private","description": "Your lovely private event","dateTimeEventCreated": "2020-08-14T17:13:38.989+00:00","eventTodos": [],"author_id": null,"group_id": null
    }
],"usersGroups": [
    {
        "publicGroupId": "GUDAIeKShEJEOE3","nameGroup": "Private","descriptionGroup": "Your lovely private group","admin_id": null,"groupEvents": [
            {
                "publicEventId": "zRmVNyS9A32OWPW","group_id": null
            }
        ],"groupTodos": null,"setUsers": []
    }
]

}

这些值确实存在于数据库中：

screenshoot of DB query

请查看我的课程（我只发布相关课程）。

UserUserClass 

@Entity(name = "users_table")
public class UserEntity implements Serializable {

private static final long serialVersionUID = -7109290743784846300L;


//******************Attributes********************

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long databaseUserId;

@Column(nullable = false)
@NaturalId
private String publicUserId;

@Column(nullable = false,length = 50)
private String name;

@Column(nullable = false,length = 10)
private String phone;

@Column(nullable = false,length = 20)
private String email;

@Column(nullable = false,length = 150)
private String userMoto;

@Column (nullable = false,length = 150)
private String encryptedPassword;



//***************** ASSOCIATIONS *******************

@OnetoMany(mappedBy = "creatorDetails",cascade = CascadeType.ALL)
private List<TodoEntity> usersTodos;

@OnetoMany(mappedBy = "adminDetails",cascade = CascadeType.ALL)
private List<GroupEntity> usersGroups;

@OnetoMany(mappedBy = "creatorDetails",cascade = CascadeType.ALL,fetch = FetchType.LAZY)
private List<EventEntity> usersEvents;


// -------------------many_to_many----------------------

@ManyToMany(fetch = FetchType.LAZY,cascade = CascadeType.ALL)
@JoinTable(name = "event_users",joinColumns = {@JoinColumn(name = "event_id")},inverseJoinColumns = {@JoinColumn(name = "user_id")}    )
private Set <EventEntity> setEvents = new HashSet<>();


@ManyToMany(fetch = FetchType.LAZY,cascade = CascadeType.ALL)
@JoinTable(name = "group_users",joinColumns = {@JoinColumn(name = "group_id")},inverseJoinColumns = {@JoinColumn(name = "user_id")}    )
private Set <GroupEntity> setGroups = new HashSet<>();

UserDto.class 

import java.io.Serializable;
import java.util.List;
import lab.alex.todo.io.entity.TodoEntity;
import lab.alex.todo.ui.model.responce.EventResponceModel;
import lab.alex.todo.ui.model.responce.GroupResponceModel;
public class UserDto implements Serializable {

private static final long serialVersionUID = -4403819017131408502L;

// ******************Attributes********************

private long databaseUserId;

private String publicUserId;

private String name;
private String phone;
private String email;

private String userMoto;

private String password;
private String encryptedPassword;

// *****************Association*******************

private List<TodoDto> usersTodos;
private List<EventResponceModel> usersEvents;
private List<GroupResponceModel> usersGroups;

// **************** Accessors **********************

UserResponceModel.class 

public class UserResponceModel {    

//******************Attributes********************

private String publicUserId;

private String name;
private String phone;
private String email;
private String userMoto;

private List<TodoResponceModel> usersTodos;
private List<EventResponceModel> usersEvents;
private List<GroupResponceModel> usersGroups;   

//****************Accessors************************

EventEntity.class 

@Entity
@Table(name="events_table")
public class EventEntity implements Serializable{

private static final long serialVersionUID = 2697897580625213781L;


//******************Attributes********************

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long databaseEventId;

    @Column(nullable = false)
    @NaturalId
    private String publicEventId;

    @Column(nullable = false,length = 50)
    private String nameEvent;

    @Column(length = 100)
    private String description;

    @Column (nullable = false,length = 30)
    @JsonFormat(shape = Shape.STRING,pattern = "dd-MM HH:mm,timezone = UTC")
    private Date dateTimeEventCreated;
    
    
    
    //*****************Association*******************
    
    @OnetoMany(mappedBy = "eventDetails",cascade = CascadeType.ALL)
    private List<TodoEntity> eventTodos;
    
    //---------------------------
    
    @ManyToOne
    @JoinColumn(name = "author_id",nullable = false,referencedColumnName = "publicUserId")
    private UserEntity creatorDetails;
    
    @ManyToOne
    @JoinColumn(name = "group_id",referencedColumnName = "publicGroupId")
    private GroupEntity eventGroupDetails;
    
    //---------------------------------
    
    @ManyToMany(fetch = FetchType.LAZY,mappedBy = "setEvents")
    private Set <UserEntity> setUsers = new HashSet<>();

EventDto.class 

public class EventDto {

//********************Attributes***************

private long databaseEventId;
private String publicEventId;
private String nameEvent;
private String description;
private Date dateTimeEventCreated;



//*****************Association*******************

private List<TodoDto> eventTodos;

//---------------------------

private String author_id;
private String group_id;

EventResponceModel.class 

public class EventResponceModel {

//********************Attributes***************


private String publicEventId;
private String nameEvent;
private String description;
private Date dateTimeEventCreated;



//*****************Association*******************

private List<TodoResponceModel> eventTodos;

//---------------------------

private String author_id;
private String group_id;

用于POSTrequest的控制器

@PostMapping
public UserResponceModel createuser(@RequestBody UserDetailsRequestModel userDetailsRequestModel) throws Exception {
    
    UserDto userDto = mapper.map(userDetailsRequestModel,UserDto.class);       
    UserDto createdUser = userService.createuser(userDto);      
    UserResponceModel returnValue = mapper.map(createdUser,UserResponceModel.class);       
    return returnValue;

该控制器的服务方法。在这里，我创建了新用户及其私有组和事件。 提醒一下-一切都将毫无问题地保存到数据库中。

@Service
public class UserServiceImpl implements UserService {
// ********************* DJs *********************

@Autowired
UserRepository userRepository;
@Autowired
GroupRepository groupRepository;
@Autowired
EventRepository eventRepository;
@Autowired
Utils utils;
@Autowired
modelmapper mapper;
@Autowired
BCryptPasswordEncoder passwordEncoder;

// **************** Methods ***************

@Override
public UserDto createuser(UserDto userDto) throws Exception {

    UserDto returnValue = new UserDto();

    if (userRepository.findByEmail(userDto.getEmail()) != null)
        throw new Exception("User already exists!");

    UserEntity newUser = mapper.map(userDto,UserEntity.class);

    // Set Public_User_Id and encrypt users password
    String publicUserId = utils.generatePublicId();
    String encryptedPassword = passwordEncoder.encode(userDto.getpassword());
    newUser.setPublicUserId(publicUserId);
    newUser.setEncryptedPassword(encryptedPassword);

    // Save new user to DB
    UserEntity createdUser = userRepository.save(newUser);


    // ********************* Create new Private group *********************
    GroupEntity newPrivateGroup = new GroupEntity();
    // Set the Admin Id
    newPrivateGroup.setAdminDetails(userRepository.findByPublicUserId(publicUserId));
    // Set the name as Private
    newPrivateGroup.setNameGroup("Private");
    // Set the description
    newPrivateGroup.setDescriptionGroup("Your lovely private group");
    // Set public id
    newPrivateGroup.setPublicGroupId(utils.generatePublicId());
    // Save new Group to DB
    GroupEntity createdGroup = groupRepository.save(newPrivateGroup);
    
    
    // ******************** Create Private Event ************************
    EventEntity newPrivatEvent = new EventEntity();
    // Set the Author Database Id (foreign Key)
    newPrivatEvent.setCreatorDetails(userRepository.findByPublicUserId(publicUserId));
    
    // Set Group Details
    newPrivatEvent.setEventGroupDetails(createdGroup);
    // set name as Private
    newPrivatEvent.setNameEvent("Private");
    // Set the description
    newPrivatEvent.setDescription("Your lovely private event");
    // Set Public_Event_Id
    newPrivatEvent.setPublicEventId(utils.generatePublicId());
    // Set Date created as current date
    newPrivatEvent.setDateTimeEventCreated(new Date());
    // Set an mpty List of todos
    newPrivatEvent.setEventTodos(new ArrayList<TodoEntity>());
    // Save new Event to DB
    EventEntity createdEvent = eventRepository.save(newPrivatEvent);
    
    
    
    // ***************** Add created Event to the List of Events in the cretedGroup
    List<EventEntity> listEvents = new ArrayList<>();
    listEvents.add(createdEvent);
    createdGroup.setGroupEvents(listEvents);
    // Update created Group
    createdGroup = groupRepository.save(createdGroup);
    
    // Add created Group and Event to the lists of groups and events of this user
    createdUser.setUsersEvents(listEvents);
    List<GroupEntity> listGroups = new ArrayList<>();
    listGroups.add(createdGroup);
    createdUser.setUsersGroups(listGroups);
    
    
    // Update createdUser,convert and send back
    createdUser = userRepository.save(createdUser);
    returnValue = mapper.map(createdUser,UserDto.class);
    return returnValue;
}

请给我指出问题出在哪里。我唯一的猜测是这是ModellMapper问题。并且我需要创建一个自定义映射器。但我对此感到怀疑

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