java - hibernate : One Entitiy class for multiple purpose?

Question

我有一个名为 Category 的实体类。我之前用它来连接另一个实体。现在我必须使用相同的 Category 实体将数据插入 类别表。

Category.java

@Entity
@Table(name = "category")
public class Category implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "category_id")
    private Integer categoryId;

    @Column(name = "category_name")
    private String categoryName;

    @NotFound(action=NotFoundAction.IGNORE)
    @JsonIgnore
    @ManyToOne
    @JoinColumn(name = "parent_category_id")
    private Category parentCategory;

    @Column(name = "created_date")
    @Temporal(javax.persistence.TemporalType.DATE)
    private Date createdDate;

    @Column(name = "last_updated_date")
    @Temporal(javax.persistence.TemporalType.DATE)
    private Date lastUpdatedDate;

    @OneToMany(mappedBy = "category")
    private List<Events> events;

    //Getters and Setters
}

Method for insert category

 @Transactional
    public UserResponse createCategory(SubmitReviewRequest createCategoryRequest) throws SQLException, ClassNotFoundException, IOException {
        Category category = new Category();
        UserResponse userResponse = new UserResponse();
        if (createCategoryRequest != null) {
            category.setCategoryName(createCategoryRequest.getSubCategory());
            // category.setParenCategoryId(Integer.parseInt(createCategoryRequest.getMainCategory()));
            int id = adminServiceDao.saveCategory(category);
            userResponse.setCode(WeekenterConstants.SUCCESS_CODE);
            userResponse.setMessage("Success");
            userResponse.setId(id);
        }

        return userResponse;
    }

问题是我必须在 Category 实体中设置 parent_category_id 才能将数据保存到 Category 表中，但我使用哪一列来加入表之前。

Table

我可以在 Category 实体中设置除 parent_category_id 之外的所有值，即 categoryId,categoryName,createdDate,lastUpdatedDate t 创建 getters 和 setters。当我尝试创建时，它显示错误 parent_category_id 列名称已使用。此错误的原因是我已使用它来加入。

Help me for use the same entity for insertion also or tell me will i need to create a separate entity for that which am not feel appropriate ?

User request sample :

{
"categoryName":"cricket",
"parentCategoryId":15
}

Answer 1

如果我理解正确的话，那么你的做法是错误的。在 hibernate 中，正确的方法是读取父类别并使用其ID(在您的情况下为1)拥有一个持久的父类别对象，然后将您尝试保留的该类别设置为parentCategory.setParentCategory(category).

@Transactional
    public UserResponse createCategory(SubmitReviewRequest createCategoryRequest) throws SQLException, ClassNotFoundException, IOException {
        Category category = new Category();
        // read parent
        Category parentCategory  = adminServiceDao.find(Integer.parseInt(createCategoryRequest.getMainCategory()));
        UserResponse userResponse = new UserResponse();
        if (createCategoryRequest != null) {
            category.setCategoryName(createCategoryRequest.getSubCategory());
            // category.setParenCategoryId(Integer.parseInt(createCategoryRequest.getMainCategory()));
            //set the child relationship.
            category.setParentCategory(parentCategory);
            int id = adminServiceDao.saveCategory(parentCategory);
            userResponse.setCode(WeekenterConstants.SUCCESS_CODE);
            userResponse.setMessage("Success");
            userResponse.setId(id);
        }

        return userResponse;
    }