双向关系在OneToMany上返回空集，并且仅在ManyToOne上起作用

如何解决双向关系在OneToMany上返回空集，并且仅在ManyToOne上起作用

我有2个实体，类别和要素，每个类别都有一个或多个要素。

在创建类别及其特征时，获取新类别将在features属性上返回一个空集。

    @PostMapping("/sub")
    @PreAuthorize("hasRole('ROLE_admin')")
    public HttpEntity<CategoryDTO> createSubCategory(@Valid @RequestBody CreateCategory createCategory)
    {
        Category category = categoryService.create(createCategory,mainCategoryService.one(createCategory.getMainCategory_id()));
        featureService.bulkCreate(createCategory.getFeatures(),category);
        return ResponseEntity.status(HttpStatus.CREATED).body(modelMapper.map(category,CategoryDTO.class));
    }

这是我发送的数据：

{"name":"SUB","mainCategory_id":1,"features":{"F1":"SLIDER","F2":"CHECKBOX"}}

这是控制器返回的数据：

{"id":2,"name":"SUB","mainCategory":{"id":1,"name":"CATEGORY"},"features":[]}

如您所见，功能为空。

这是创建具有以下功能的类别的测试：

    @Test
    public void testIfAdminCanCreateSubCategory_expect201AndMainCategoryIdEqualsTheAssociatedOne() throws Exception {
        String category = "{\"name\" : \"CATEGORY\"}";
        String sub = "{\"name\":\"SUB\",\"mainCategory_id\":1,\"features\":{\"F1\":\"SLIDER\",\"F2\":\"CHECKBOX\"}}";
        mockMvc().with(keycloakAuthenticationToken().authorities("ROLE_admin")).perform(post("/categories").content(category).contentType("application/json"))
                .andDo(print())
                .andDo(r -> mockMvc().with(keycloakAuthenticationToken().authorities("ROLE_admin"))
                        .post(sub,"/categories/sub")
                        .andExpect(status().isCreated())
                        .andExpect(jsonPath("$.mainCategory.id").value(1))
                        .andDo(print())
                       // .andExpect(jsonPath("$.features[0]").value("SLIDER"))
                );
        //featureService.all().forEach( f -> System.out.println(f.getCategory().getId()));
    }

在对最后一行进行注释时，它会打印类别ID（在返回的数据中显示为2），这意味着ManyToOne正在工作，但OneToMany却不在。

我的模特：

@Entity
@EntityListeners( AuditingEntityListener.class  )
@Data
public class Category {

    @Id @GeneratedValue(strategy=GenerationType.AUTO) private Long id;
    ....
    @OneToMany(cascade = CascadeType.ALL,mappedBy = "category",fetch = FetchType.LAZY)
    Set<Feature> features = new HashSet<>();
}

@Entity
@Data
public class Feature {
    @Id @GeneratedValue private Long id;
    private String name;
    private FeatureType type;
    @ManyToOne Category category;
}

categoryService中的create方法：

    @Override
    public Category create(CreateCategory createCategory,MainCategory mainCategory) {
        Category category = new Category();
        category.setName(createCategory.getName().toUpperCase());
        category.setMainCategory(mainCategory);
        return categoryRepository.save(category);
    }

featureService中的bulkCreate方法：

    @Override
    public Feature create(String feature,FeatureType type,Category category) {
        Feature f = new Feature();
        f.setName(feature);
        f.setType(type);
        f.setCategory(category);
        return featureRepository.save(f);
    }

    @Override
    public void bulkCreate(Map<String,FeatureType> features,Category category) {
        features.forEach( (name,type) -> create(name,type,category));
    }

myDTO：

@Data
public class CategoryDTO {
    private Long id;
    private String name;
    private MainCategoryDTO mainCategory;
    private Set<FeatureDTO> features;
}

@Data
public class FeatureDTO {
    private Long id;
    private String name;
    private FeatureType type;
}

@Data
public class MainCategoryDTO {
    private Long id;
    private String name;
}

编辑1 ：

我在我的categoryService上添加了一个设置类别功能的方法。

    @Override
    public Category addFeatures(Category category,List<Feature> features) {
        category.setFeatures(features);
        return categoryRepository.save(category);
    }

在我的控制器上，我添加了注释行，以便可以将要素关联到类别

    @PostMapping("/sub")
    @PreAuthorize("hasRole('ROLE_admin')")
    public HttpEntity<CategoryDTO> createSubCategory(@Valid @RequestBody CreateCategory createCategory)
    {
        Category category = categoryService.create(createCategory,mainCategoryService.one(createCategory.getMainCategory_id()));
        #category = categoryService.addFeatures(category,featureService.bulkCreate(createCategory.getFeatures(),category));
        return ResponseEntity.status(HttpStatus.CREATED).body(modelMapper.map(category,CategoryDTO.class));
    }