java - Hibernate自动删除多对多关系

Question

我有一个应该是多对多(双向)的列表

这是过滤器类:

@ManyToMany(targetEntity=Serving.class)
@JoinTable(name = "BRIDGE_SERV_FILTER", joinColumns={
    @JoinColumn(name="filter_id")}, inverseJoinColumns={@JoinColumn(name="serving_id")})
private List<Serving> servings;
public List<Serving> getServing() { return this.servings; }
public void setServing(List<Serving> servings) { this.servings = servings; }

这是服务类:

@ManyToMany(targetEntity=Filter.class)
    @JoinTable(name = "BRIDGE_SERV_FILTER", joinColumns={
        @JoinColumn(name="serving_id")}, inverseJoinColumns={@JoinColumn(name="filter_id")})
    private List<Filter> filters;
    public List<Filter> getFilters() { return filters;}
    public void setFilters(List<Filter> filters) { this.filters = filters;}

然后我应该调用一些东西从服务中获取所有过滤器，这就是我所做的(serv 是 Serving 类型):

List<Filter> filters = serv.getFilters();

//iterate from all filter
for(Filter allf : allFilter)
{
    boolean mark_this = false;
    //..and matched the currently-iterated-all-filters with filter from
    //which the serving got
    for(com.pos.model.Filter f : filters)
    {
        //if matched, mark this current filter
        if (allf.getId().equals(f.getId()))
            mark_this = true;
    }
    tmodel.addRow(new Object[] { allf.getName(), mark_this });
}

该方法在模型中定义，并且是静态的。所以，当表单加载时，它会调用 jTable.setTableModel(Filter.toTableModel(thisServing));

它读取并显示数据。然而，Hibernate 也调用删除:

Hibernate: select filter0_.filter_id as filter1_2_, filter0_.is_showable as is2_2_, filter0_.name as name2_ from DIM_FILTER filter0_ where is_showable=true
Hibernate: select filters0_.serving_id as serving1_4_1_, filters0_.filter_id as filter2_6_1_, filter1_.filter_id as filter1_2_0_, filter1_.is_showable as is2_2_0_, filter1_.name as name2_0_ from BRIDGE_SERV_FILTER filters0_ inner join DIM_FILTER filter1_ on filters0_.filter_id=filter1_.filter_id where filters0_.serving_id=?
Hibernate: delete from BRIDGE_SERV_FILTER where serving_id=?

事实上，我根本不做任何删除，也不要求hibernate删除任何东西。可能会发生一些我不明白的事情……如何防止 Hibernate 被删除？还是我做错了什么？

Answer 1

在您的代码中的某处，您必须清除服务的过滤器集合，或将此集合设置为空。 Hibernate 使这种变化持久化。

另请注意，您的映射是错误的，这就是您看到奇怪行为的原因。您没有双向 ManyToMany，而是有两个不相关的单向 ManyToMany，它们都使用相同的连接表。必须选择其中一侧作为另一侧的倒数。例如，如果您希望过滤器端成为关联的所有者，则必须使用 mappedBy 属性将服务端标记为反面:

class Filter {
    @ManyToMany
    @JoinTable(name = "BRIDGE_SERV_FILTER", joinColumns={
    @JoinColumn(name="filter_id")}, inverseJoinColumns={@JoinColumn(name="serving_id")})
    private List<Serving> servings;
}

class Serving {
    @ManyToMany(mappedBy = "servings")
    private List<Filter> filters;
}

这在 the documentation 中有描述.