Question

我有2个实体，通过一对一依赖关系进行连接。

用户：

public class User {

    @OneToOne(cascade = [CascadeType.ALL], fetch = FetchType.EAGER, mappedBy = "user")
    private UserParams params;
    ...
}

UserParams：

public class UserParams {

    @OneToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "user_id")
    private User user;
    ...
}

我用ModelMapper对其进行了转换：

@Bean
public ModelMapper modelMapper() {
    ModelMapper mapper = new ModelMapper();
    mapper.getConfiguration()
            .setMatchingStrategy(MatchingStrategies.STRICT)
            .setFieldMatchingEnabled(true)
            .setSkipNullEnabled(true)
            .setPropertyCondition(Conditions.isNotNull())
            .setFieldAccessLevel(PRIVATE);
    return mapper;
}

我将解释mapper的工作原理。我从UserParams映射中排除“用户”字段，并将其单独映射。这样，我只接收UserParams的'user'字段的ID和User的完整dto'params'。

//exclude from mapping
@PostConstruct
public void init() {
    mapper.createTypeMap(UserParams.class, UserParamsDto.class)
            .addMappings(m -> m.skip(UserParamsDto::setUser)).setPostConverter(toDtoConverter());
    mapper.createTypeMap(UserParamsDto.class, UserParams.class)
            .addMappings(m -> m.skip(UserParams::setUser)).setPostConverter(toEntityConverter());
}

//map separately
@Override
protected void mapSpecificFields(UserParams source, UserParamsDto destination) {
    whenNotNull(source.getUser(), u -> destination.setUser(u.getId()));
}

@Override
protected void mapSpecificFields(UserParamsDto source, UserParams destination) {
    whenNotNull(source.getUser(), u -> destination.setUser(userRepository.findById(u).orElse(null)));
}

后转换器实现转换：

protected Converter<E, D> toDtoConverter() {
    return context -> {
        E source = context.getSource();
        D destination = context.getDestination();
        mapSpecificFields(source, destination);
        return context.getDestination();
    };
}

protected Converter<D, E> toEntityConverter() {
    return context -> {
        D source = context.getSource();
        E destination = context.getDestination();
        mapSpecificFields(source, destination);
        return context.getDestination();
    };
}

然后，当我调用UserParams（通过/ params？id = 1）时，我使用已填充的用户重新接收JSON：

{
    "id": 5,
    "created": "2019-06-13T20:07:52.221",
    "updated": null,
    "user": 1,
    "height": 180,
    "weight": 75,
    "gender": null,
    "birthDate": null
}

但是当我打电话给用户时，字段参数会转换为dto（字段用户除外）：

{
    "id": 1,
    "created": "2019-06-13T19:50:16",
    "updated": null,
    "params": {
        "id": 2,
        "created": "2019-06-13T19:50:22",
        "updated": null,
        "user": null,    //null
        "height": 180,
        "weight": 75,
        "gender": null,
        "birthDate": null
    }
}

据我了解，当映射用户时，映射器不为嵌套对象调用postConverter，我使用断点进行了检查。为什么？该怎么办？项目here。

Modelmapper返回null代替用户ID

0 个答案: