Question

我有一个子实体和两个父实体，每个父实体都有一个子实体列表。如果我通过首先获取Parent_1的子节点然后将该列表分配给Parent_2 hibernate来创建Parent_2的子实体列表，则按照以下代码删除“Parent_1-Child”连接表记录。

Parent_1：

@Entity
@Table
public class Parent_1 extends BusinessObject {

    List<Child> children = new ArrayList<Child>();

    public Parent_1() {}

    public Parent_1(List<Child> children) {
        this.children = children;
    }

    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(name = "parent1_children", joinColumns = @JoinColumn(name = "parent1_id"), inverseJoinColumns = @JoinColumn(name = "child_id"))
    @OrderColumn(name = "child_order")
    public List<Child> getChildren() {
        return children;
    }

    public void setChildren(List<Child> children) {
        this.children = children;
    }

}

Parent_2：

@Entity
@Table
public class Parent_2 extends BusinessObject {

    List<Child> children = new ArrayList<Child>();

    public Parent_2() {}

    public Parent_2(List<Child> children) {
        this.children = children;
    }


    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(name = "parent2_children", joinColumns = @JoinColumn(name = "parent2_id"), inverseJoinColumns = @JoinColumn(name = "child_id"))
    @OrderColumn(name = "child_order")
    public List<Child> getChildren() {
        return children;
    }

    public void setChildren(List<Child> children) {
        this.children = children;
    }

}

儿童：

@Entity
@Table
public class Child extends BusinessObject {

    public Child() {}

}

我运行的代码遇到错误：

@Test
public void demoTest() {
    Child child_1 = new Child();
    Child child_2 = new Child();
    save(child_1, child_2);

    List<Child> children = new ArrayList<Child>();
    children.add(child_1);
    children.add(child_2);

    Parent_1 parent_1 = new Parent_1(children);
    Parent_1 parent_1_1 = new Parent_1(children);
    save(parent_1, parent_1_1);

    Parent_1 existingParent = dataAccessService.getParentById(new Long(1));
    List<Child> newChildren = existingParent.getChildren();

    Parent_2 parent_2 = new Parent_2(newChildren);
    save(parent_2);
}

这是上次保存时执行的SQL：

Hibernate: 
    insert 
    into
        Parent_2
        (created, deleted, hidden, lastModified, id) 
    values
        (?, ?, ?, ?, ?)
Hibernate: 
    delete 
    from
        parent1_children 
    where
        parent1_id=?
Hibernate: 
    insert 
    into
        parent2_children
        (parent2_id, child_order, child_id) 
    values
        (?, ?, ?)
Hibernate: 
    insert 
    into
        parent2_children
        (parent2_id, child_order, child_id) 
    values
        (?, ?, ?)

问题在于删除语句。为什么hibernate会执行此操作，我该怎么做才能阻止它发生？

RGDS，菲尔

注意：BusinessObject只是按照以下方式证明每个表的id：

@Id
@GeneratedValue(strategy = GenerationType.TABLE)
public Long getId(){
    return id;
}

Answer 1

我能给你的最佳答案是它在hibernate上似乎可以正常工作。我重新创建了你的课程。我把注释放在字段而不是方法上，但我认为这没有任何区别。我在Wildfly 9.0.2.Final上将其作为JPA运行。我看到您正在使用Spring持久性API。我没有尝试重现，但我认为你的问题是可重复的。

Hibernate从相关联接表中删除多个多对多关系中的数据

1 个答案: