java - Hibernate5 update only collection 多对多关系

Question

我用 Hibernate 5.2 映射了下图

这些是我的实体类:

股票

@Entity
@Table(name = "stock", catalog = "mkyongdb", uniqueConstraints = {
        @UniqueConstraint(columnNames = "STOCK_NAME"),
        @UniqueConstraint(columnNames = "STOCK_CODE") })
public class Stock implements java.io.Serializable {

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "STOCK_ID", unique = true, nullable = false)
    private Integer stockId;

    @Column(name = "STOCK_CODE", unique = true, nullable = false, length = 10)
    private String stockCode;

    @Column(name = "STOCK_NAME", unique = true, nullable = false, length = 20)
    private String stockName;

    @ManyToMany(fetch = FetchType.LAZY, cascade = {CascadeType.MERGE, CascadeType.REFRESH})
    @JoinTable(name = "stock_category", catalog = "mkyongdb", joinColumns = {
            @JoinColumn(name = "STOCK_ID", nullable = false, updatable = false) },
            inverseJoinColumns = { @JoinColumn(name = "CATEGORY_ID",
                    nullable = false, updatable = false) })
    private Set<Category> categories = new HashSet<>();

    //Getter and Setter

}

类别

@Entity
@Table(name = "category", catalog = "mkyongdb")
public class Category implements java.io.Serializable {

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "CATEGORY_ID", unique = true, nullable = false)
    private Integer categoryId;

    @Column(name = "NAME", nullable = false, length = 10)
    private String name;

    @Column(name = "[DESC]", nullable = false)
    private String desc;

    @ManyToMany(fetch = FetchType.LAZY, mappedBy = "categories", cascade = {CascadeType.MERGE, CascadeType.REFRESH})
    private Set<Stock> stocks = new HashSet<>();

    //Getter and Setter

}

一切正常。

我需要做的只是为一只股票添加一个类别列表。我不想修改 Stock 实体，只是在 stock_category 表中添加或删除类别。

这是我的服务:

@Override
@Transactional(rollbackFor = StockException.class)
public void addCategoriesToStock(Set<Category> categories, Stock stock) throws StockException{
    stock = sessionFactory.getCurrentSession().get(Stock.class, stock.getCodStock());
    stock.setCategories(categories);
    sessionFactory.getCurrentSession().update(stock);
    sessionFactory.getCurrentSession().flush();
}

这是对服务的测试

@Test
public void testAddCategoriesStock() throws Exception {
    Stock newValues = new Stock();
    newValues.setStockId(1);
    Category category = new Category();
    category.setCategoryId(13);
    dao.addCategoriesToStock(new HashSet<>(Arrays.asList(category)), newValues);
    List<Stock> stocks = dao.getAllStockeByCategoriesCriteria(category);
    for (Stock stock : stocks) {
        System.out.println(stock);
    }
}

测试运行良好，没有错误，但是当浏览与类别“13”(getAllStockeByCategoriesCriteria)关联的股票时，它没有给我带来任何股票。那么之前执行的操作没有生效。

如何添加或删除类别？

Answer 1

您必须在两侧添加依赖项，因此您缺少将 Stock 添加到 categories 中:

@Override
@Transactional(rollbackFor = StockException.class)
public void addCategoriesToStock(List<Category> categories, Stock stock) throws StockException{
    stock = sessionFactory.getCurrentSession().get(Stock.class, stock.getCodStock());
    stock.setCategories(categories);

    for(Category cat: categories){
        cat.getStocks().add(stock);
    }

    sessionFactory.getCurrentSession().merge(stock);
    sessionFactory.getCurrentSession().flush();
}

此外，我认为您应该使用 merge 而不是 update 来使级联工作。

之后您的代码应保存关系。