Java 有没有办法防止MapStruct在更新记录期间覆盖值？

我看到2018年有一个类似的问题： 但没有解决这个问题的例子

因此，我不知道如何解决它

我正在使用

Lombok

和

MapStruct

UserEntity

表示数据库中的表

@Getter
@Setter
@Entity
@Table(name = "users")
public class UserEntity implements Serializable {

    private static final long serialVersionUID = -3549451006888843499L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)     // this specifies that the id will be auto-incremented by the database
    private Long id;
    
    @Column( nullable = false)
    private String userId;
    
    @Column( nullable = false, length = 50)
    private String firstName;
    
    @Column( nullable = false, length = 50)
    private String lastName;
    
    @Column( nullable = false, length = 120)
    private String email;
    
    @Column( nullable = false)
    private String encryptedPassword;   // I am encrypting the password during first insertion of a new record

}// end of class

UserDTO

用作

UserEntity

和

UserRequestModel

之间的中介（我将在后面提到）

UserRequestModel

在请求到达UserController时使用

@Getter
@Setter
@ToString
public class UserRequestModel {
    
//  ------------------------------------------------------
//  Attributes
//  ------------------------------------------------------
    private String firstName;
    private String lastName;
    private String email;
    
}// end of class

我创建了一个

UserMapper

接口，供

MapStruct

使用

@Mapper(componentModel = "spring", nullValuePropertyMappingStrategy = NullValuePropertyMappingStrategy.IGNORE)
public interface UserMapper {

    @Mapping(target = "password", ignore = true)
    UserDTO mapEntityToDto(UserEntity userEntity);

    @Mapping(target = "encryptedPassword")
    UserEntity mapDtoToEntity(UserDTO userDto);
    
    UserResponseModel mapDtoToResponseModel(UserDTO userDto);
    
    @Mapping(target = "encryptedPassword", ignore = true)
    @Mapping(target = "id", ignore = true)
    @Mapping(target = "userId", ignore = true)
    UserDTO mapUserRequestModelToDto(UserRequestModel userRequestModel);
    
}// end of interface

最后，我使用

UserResponseModel

将记录返回给客户端应用程序

@Getter
@Setter
@ToString
public class UserResponseModel {
    
//  ------------------------------------------------------
//  Attributes
//  ------------------------------------------------------
    
    // This is NOT the actual usedId in the database!!!
    // We should not provide the actual value. For security reasons.
    // Think of it as a public user id.
    private String userId;
    private String firstName;
    private String lastName;
    private String email;

}// end of class

@Override
public UserDTO updateUser(String userId, UserDTO user) {
        
    UserDTO returnValue = new UserDTO();
        
    UserEntity userEntity = userRepository.findByUserId(userId);
        
    if(userEntity == null) {
        throw new UserServiceException("No record found with the specific id!");        // our own exception
    }
        
    // get the changes from the DTO and map them to the Entity
    // this did not work. The values of the Entity were set to null if they were not assigned in the DTO
    userEntity = userMapper.mapDtoToEntity(user);
        
    // If I set the values of the Entity manually, then it works
//      userEntity.setFirstName(user.getFirstName());
//      userEntity.setLastName(user.getLastName());
//      userEntity.setEmail(user.getEmail());
        
    // save the Entity
    userRepository.save(userEntity);
        
    returnValue = userMapper.mapEntityToDto(userEntity);
        
    return returnValue;
        
}// end of updateUser

上面的对象用于映射。现在，我将向您展示

UserController

和

UserService

中的代码。此问题发生在

UserService

类中

@PutMapping(path = "/{id}")
public UserResponseModel updateUser(@PathVariable("id") String id , @RequestBody UserRequestModel userRequestModel) {
        
    UserResponseModel returnValue = new UserResponseModel();
        
    UserDTO userDTO = userMapper.mapUserRequestModelToDto(userRequestModel);
        
    // call the method to update the user and return the updated object as a UserDTO
    UserDTO updatedUser = userService.updateUser(id, userDTO);
        
    returnValue = userMapper.mapDtoToResponseModel(updatedUser);
        
    return returnValue;
        
}// end of updateUser

@Mapping(target = "firstName", source = "firstName")
@Mapping(target = "lastName", source = "lastName")
@Mapping(target = "email", source = "email")
void updateFields(@MappingTarget UserEntity entity, UserDTO dto);

@Override
public UserDTO updateUser(String userId, UserDTO user) {
        
    UserDTO returnValue = new UserDTO();

    UserEntity userEntity = userRepository.findByUserId(userId);

    if (userEntity == null)
            throw new UserServiceException(ErrorMessages.NO_RECORD_FOUND.getErrorMessage());
        
    // update only specific fields of userEntity
    userMapper.updateFields( userEntity, user);

    userRepository.save(userEntity);
        
    // map again UserEntity to UserDTO in order to send it back
    returnValue = userMapper.mapEntityToDto(userEntity);

    return returnValue;
        
}// end of updateUser

UserService

用于实现应用程序的业务逻辑

@Getter
@Setter
@ToString
public class UserResponseModel {
    
//  ------------------------------------------------------
//  Attributes
//  ------------------------------------------------------
    
    // This is NOT the actual usedId in the database!!!
    // We should not provide the actual value. For security reasons.
    // Think of it as a public user id.
    private String userId;
    private String firstName;
    private String lastName;
    private String email;

}// end of class

@Override
public UserDTO updateUser(String userId, UserDTO user) {
        
    UserDTO returnValue = new UserDTO();
        
    UserEntity userEntity = userRepository.findByUserId(userId);
        
    if(userEntity == null) {
        throw new UserServiceException("No record found with the specific id!");        // our own exception
    }
        
    // get the changes from the DTO and map them to the Entity
    // this did not work. The values of the Entity were set to null if they were not assigned in the DTO
    userEntity = userMapper.mapDtoToEntity(user);
        
    // If I set the values of the Entity manually, then it works
//      userEntity.setFirstName(user.getFirstName());
//      userEntity.setLastName(user.getLastName());
//      userEntity.setEmail(user.getEmail());
        
    // save the Entity
    userRepository.save(userEntity);
        
    returnValue = userMapper.mapEntityToDto(userEntity);
        
    return returnValue;
        
}// end of updateUser

如果我尝试运行此代码，则会出现以下错误

我使用调试器来理解这个问题，我注意到

MapStruct

正在覆盖所有属性，而不仅仅是请求中发送的属性

MapStruct

自动生成的代码如下：

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2020-11-01T11:56:36+0200",
    comments = "version: 1.4.1.Final, compiler: Eclipse JDT (IDE) 3.21.0.v20200304-1404, environment: Java 11.0.9 (Ubuntu)"
)
@Component
public class UserMapperImpl implements UserMapper {

    @Override
    public UserDTO mapEntityToDto(UserEntity userEntity) {
        if ( userEntity == null ) {
            return null;
        }

        UserDTO userDTO = new UserDTO();

        userDTO.setEmail( userEntity.getEmail() );
        userDTO.setEncryptedPassword( userEntity.getEncryptedPassword() );
        userDTO.setFirstName( userEntity.getFirstName() );
        userDTO.setId( userEntity.getId() );
        userDTO.setLastName( userEntity.getLastName() );
        userDTO.setUserId( userEntity.getUserId() );

        return userDTO;
    }

    @Override
    public UserEntity mapDtoToEntity(UserDTO userDto) {
        if ( userDto == null ) {
            return null;
        }

        UserEntity userEntity = new UserEntity();

        userEntity.setEncryptedPassword( userDto.getEncryptedPassword() );
        userEntity.setEmail( userDto.getEmail() );
        userEntity.setFirstName( userDto.getFirstName() );
        userEntity.setId( userDto.getId() );
        userEntity.setLastName( userDto.getLastName() );
        userEntity.setUserId( userDto.getUserId() );

        return userEntity;
    }

    @Override
    public UserResponseModel mapDtoToResponseModel(UserDTO userDto) {
        if ( userDto == null ) {
            return null;
        }

        UserResponseModel userResponseModel = new UserResponseModel();

        userResponseModel.setEmail( userDto.getEmail() );
        userResponseModel.setFirstName( userDto.getFirstName() );
        userResponseModel.setLastName( userDto.getLastName() );
        userResponseModel.setUserId( userDto.getUserId() );

        return userResponseModel;
    }

    @Override
    public UserDTO mapUserRequestModelToDto(UserRequestModel userRequestModel) {
        if ( userRequestModel == null ) {
            return null;
        }

        UserDTO userDTO = new UserDTO();

        userDTO.setEmail( userRequestModel.getEmail() );
        userDTO.setFirstName( userRequestModel.getFirstName() );
        userDTO.setLastName( userRequestModel.getLastName() );
        userDTO.setPassword( userRequestModel.getPassword() );

        return userDTO;
    }
}

@Mapping(target = "targetFieldName", source = "sourceFieldName")
void updateFields(@MappingTarget UserEntity entity, UserDTO dto);

很可能，我做的事情不对

你认为问题的出现是因为我没有构造函数吗？通常，如果我们不实现无参数构造函数，Java会自动创建它

我正在添加下图，以便演示我想做的事情。也许这种流动能有所帮助

很可能方法

MapdToEntity

应该接受两个属性，以便将

UserDTO

映射到

UserEntity

。例如：

userMapper.mapDtoToEntity(userDto, userEntity);

谢谢你！！！我在我的代码中添加了你的修改，一切正常

更新版本

我不得不将以下方法添加到

UserMapper

类中

@PutMapping(path = "/{id}")
public UserResponseModel updateUser(@PathVariable("id") String id , @RequestBody UserRequestModel userRequestModel) {
        
    UserResponseModel returnValue = new UserResponseModel();
        
    UserDTO userDTO = userMapper.mapUserRequestModelToDto(userRequestModel);
        
    // call the method to update the user and return the updated object as a UserDTO
    UserDTO updatedUser = userService.updateUser(id, userDTO);
        
    returnValue = userMapper.mapDtoToResponseModel(updatedUser);
        
    return returnValue;
        
}// end of updateUser

@Mapping(target = "firstName", source = "firstName")
@Mapping(target = "lastName", source = "lastName")
@Mapping(target = "email", source = "email")
void updateFields(@MappingTarget UserEntity entity, UserDTO dto);

@Override
public UserDTO updateUser(String userId, UserDTO user) {
        
    UserDTO returnValue = new UserDTO();

    UserEntity userEntity = userRepository.findByUserId(userId);

    if (userEntity == null)
            throw new UserServiceException(ErrorMessages.NO_RECORD_FOUND.getErrorMessage());
        
    // update only specific fields of userEntity
    userMapper.updateFields( userEntity, user);

    userRepository.save(userEntity);
        
    // map again UserEntity to UserDTO in order to send it back
    returnValue = userMapper.mapEntityToDto(userEntity);

    return returnValue;
        
}// end of updateUser

然后，我不得不修改

UserService

类中的

updateUser

方法

@PutMapping(path = "/{id}")
public UserResponseModel updateUser(@PathVariable("id") String id , @RequestBody UserRequestModel userRequestModel) {
        
    UserResponseModel returnValue = new UserResponseModel();
        
    UserDTO userDTO = userMapper.mapUserRequestModelToDto(userRequestModel);
        
    // call the method to update the user and return the updated object as a UserDTO
    UserDTO updatedUser = userService.updateUser(id, userDTO);
        
    returnValue = userMapper.mapDtoToResponseModel(updatedUser);
        
    return returnValue;
        
}// end of updateUser

@Mapping(target = "firstName", source = "firstName")
@Mapping(target = "lastName", source = "lastName")
@Mapping(target = "email", source = "email")
void updateFields(@MappingTarget UserEntity entity, UserDTO dto);

@Override
public UserDTO updateUser(String userId, UserDTO user) {
        
    UserDTO returnValue = new UserDTO();

    UserEntity userEntity = userRepository.findByUserId(userId);

    if (userEntity == null)
            throw new UserServiceException(ErrorMessages.NO_RECORD_FOUND.getErrorMessage());
        
    // update only specific fields of userEntity
    userMapper.updateFields( userEntity, user);

    userRepository.save(userEntity);
        
    // map again UserEntity to UserDTO in order to send it back
    returnValue = userMapper.mapEntityToDto(userEntity);

    return returnValue;
        
}// end of updateUser

---

事实上，每次执行PUT时，您都在创建一个新的

UserEntity

实例。应该做的是更新所需字段。为此，您可以按如下方式使用

@MappingTarget

：

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2020-11-01T11:56:36+0200",
    comments = "version: 1.4.1.Final, compiler: Eclipse JDT (IDE) 3.21.0.v20200304-1404, environment: Java 11.0.9 (Ubuntu)"
)
@Component
public class UserMapperImpl implements UserMapper {

    @Override
    public UserDTO mapEntityToDto(UserEntity userEntity) {
        if ( userEntity == null ) {
            return null;
        }

        UserDTO userDTO = new UserDTO();

        userDTO.setEmail( userEntity.getEmail() );
        userDTO.setEncryptedPassword( userEntity.getEncryptedPassword() );
        userDTO.setFirstName( userEntity.getFirstName() );
        userDTO.setId( userEntity.getId() );
        userDTO.setLastName( userEntity.getLastName() );
        userDTO.setUserId( userEntity.getUserId() );

        return userDTO;
    }

    @Override
    public UserEntity mapDtoToEntity(UserDTO userDto) {
        if ( userDto == null ) {
            return null;
        }

        UserEntity userEntity = new UserEntity();

        userEntity.setEncryptedPassword( userDto.getEncryptedPassword() );
        userEntity.setEmail( userDto.getEmail() );
        userEntity.setFirstName( userDto.getFirstName() );
        userEntity.setId( userDto.getId() );
        userEntity.setLastName( userDto.getLastName() );
        userEntity.setUserId( userDto.getUserId() );

        return userEntity;
    }

    @Override
    public UserResponseModel mapDtoToResponseModel(UserDTO userDto) {
        if ( userDto == null ) {
            return null;
        }

        UserResponseModel userResponseModel = new UserResponseModel();

        userResponseModel.setEmail( userDto.getEmail() );
        userResponseModel.setFirstName( userDto.getFirstName() );
        userResponseModel.setLastName( userDto.getLastName() );
        userResponseModel.setUserId( userDto.getUserId() );

        return userResponseModel;
    }

    @Override
    public UserDTO mapUserRequestModelToDto(UserRequestModel userRequestModel) {
        if ( userRequestModel == null ) {
            return null;
        }

        UserDTO userDTO = new UserDTO();

        userDTO.setEmail( userRequestModel.getEmail() );
        userDTO.setFirstName( userRequestModel.getFirstName() );
        userDTO.setLastName( userRequestModel.getLastName() );
        userDTO.setPassword( userRequestModel.getPassword() );

        return userDTO;
    }
}

@Mapping(target = "targetFieldName", source = "sourceFieldName")
void updateFields(@MappingTarget UserEntity entity, UserDTO dto);

---

此注释确保不创建新对象，它将维护原始对象，只更新所需字段。

事实上，每次执行PUT时，您都在创建一个新的

UserEntity

实例。应该做的是更新所需字段。为此，您可以按如下方式使用

@MappingTarget

：

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2020-11-01T11:56:36+0200",
    comments = "version: 1.4.1.Final, compiler: Eclipse JDT (IDE) 3.21.0.v20200304-1404, environment: Java 11.0.9 (Ubuntu)"
)
@Component
public class UserMapperImpl implements UserMapper {

    @Override
    public UserDTO mapEntityToDto(UserEntity userEntity) {
        if ( userEntity == null ) {
            return null;
        }

        UserDTO userDTO = new UserDTO();

        userDTO.setEmail( userEntity.getEmail() );
        userDTO.setEncryptedPassword( userEntity.getEncryptedPassword() );
        userDTO.setFirstName( userEntity.getFirstName() );
        userDTO.setId( userEntity.getId() );
        userDTO.setLastName( userEntity.getLastName() );
        userDTO.setUserId( userEntity.getUserId() );

        return userDTO;
    }

    @Override
    public UserEntity mapDtoToEntity(UserDTO userDto) {
        if ( userDto == null ) {
            return null;
        }

        UserEntity userEntity = new UserEntity();

        userEntity.setEncryptedPassword( userDto.getEncryptedPassword() );
        userEntity.setEmail( userDto.getEmail() );
        userEntity.setFirstName( userDto.getFirstName() );
        userEntity.setId( userDto.getId() );
        userEntity.setLastName( userDto.getLastName() );
        userEntity.setUserId( userDto.getUserId() );

        return userEntity;
    }

    @Override
    public UserResponseModel mapDtoToResponseModel(UserDTO userDto) {
        if ( userDto == null ) {
            return null;
        }

        UserResponseModel userResponseModel = new UserResponseModel();

        userResponseModel.setEmail( userDto.getEmail() );
        userResponseModel.setFirstName( userDto.getFirstName() );
        userResponseModel.setLastName( userDto.getLastName() );
        userResponseModel.setUserId( userDto.getUserId() );

        return userResponseModel;
    }

    @Override
    public UserDTO mapUserRequestModelToDto(UserRequestModel userRequestModel) {
        if ( userRequestModel == null ) {
            return null;
        }

        UserDTO userDTO = new UserDTO();

        userDTO.setEmail( userRequestModel.getEmail() );
        userDTO.setFirstName( userRequestModel.getFirstName() );
        userDTO.setLastName( userRequestModel.getLastName() );
        userDTO.setPassword( userRequestModel.getPassword() );

        return userDTO;
    }
}

@Mapping(target = "targetFieldName", source = "sourceFieldName")
void updateFields(@MappingTarget UserEntity entity, UserDTO dto);

---

此注释确保不创建新对象，它将维护原始对象，只更新所需的字段。

我不确定是否理解UserEntity中字段“userId”和“id”的含义。它是否引用外键？如果是这种情况，您可以在持久化实体之前注入父（或子）对象。Hello@Sergio，我正在使用UserEntity中的id来表示表的主键。出于安全原因，我不想将此id发送到客户端应用程序。因此，我创建了一个用户ID，用作公钥。您使用哪个数据库？我不确定是否理解公钥的概念。它是否引用数据库中的另一个表？因为在您显示的错误消息中，两个表之间的链接似乎不满足要求。我只有一个名为UserEntity的表，它具有一个名为id的自动递增主键。因为我不想向客户端应用程序显示主键的实际值，所以我使用了另一个名为userId的属性。这是出于安全考虑我想要的东西。出现此问题的原因是MapStruct创建了一个新的UserEntity，并且UserEntity中的值encryptedPassword设置为NULL。encryptedPassword不能为空！也许您没有复制它，但我看不到从密码到encryptedPassword的位置，因为它不在来自控制器的传入UserRequestModel中。您是否为encryptedPassword生成随机值？我不确定您的UserEntity中“userId”和“id”字段的含义。它是否引用外键？如果是这种情况，您可以在持久化实体之前注入父（或子）对象。Hello@Sergio，我正在使用UserEntity中的id来表示表的主键。出于安全原因，我不想将此id发送到客户端应用程序。因此，我创建了一个用户ID，用作公钥。您使用哪个数据库？我不确定是否理解公钥的概念。它是否引用数据库中的另一个表？因为在您显示的错误消息中，两个表之间的链接似乎不满足要求。我只有一个名为UserEntity的表，它具有一个名为id的自动递增主键。因为我不想向客户端应用程序显示主键的实际值，所以我使用了另一个名为userId的属性。这是出于安全考虑我想要的东西。出现此问题的原因是MapStruct创建了一个新的UserEntity，并且UserEntity中的值encryptedPassword设置为NULL。encryptedPassword不能为空！也许您没有复制它，但我看不到从密码到encryptedPassword的位置，因为它不在来自控制器的传入UserRequestModel中。您是否为encryptedPassword生成随机值？谢谢@Sergio！修改后一切正常！！！谢谢你@Sergio！修改后一切正常！！！