hibernate - 拥有级联 ="all-delete-orphan"的集合不再被拥有的实体实例引用

Question

在我的应用程序中， hibernate 操作是这样的。
应用程序使用请求中的新值更新父实体，并删除所有现有(之前插入的)子实体并插入新的子记录。

我正在使用 hibernate 模式 DELETE_ORPHAN为此，如下所示。

当我这样做时，我收到以下异常:

org.hibernate.HibernateException: A collection with cascade="all-delete-orphan" was no longer referenced by the owning entity instance: com.childs

我看到了与该问题类似的线程，并尝试在这些线程中应用解决方案。但这没有用

我的父实体

    public class Parent implements Serializable {

            @Column(name = "PARENT_ID")
            @Basic(fetch = FetchType.EAGER)
            @Id
            @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seq")
            @SequenceGenerator(name = "seq", sequenceName = "seq")
            private Integer parentId;  //primary key of parent

            ....... 
            ........

            //mapping to child entity
            @OneToMany(mappedBy = "parent", cascade = { CascadeType.ALL }, fetch =  FetchType.LAZY)
            @Cascade(org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
            private Set<Child> childs;

            ................
            ...............

}

子实体有一个组合键并有一个PK实体如下所示

public class ChildPK implements Serializable {

    /** The Constant serialVersionUID. */
    private static final long serialVersionUID = -447592368963477750L;

    /** . */
    @ManyToOne(cascade = { CascadeType.ALL }, fetch = FetchType.LAZY)
    @JoinColumns( { @JoinColumn(name = "PARENT_ID", referencedColumnName = "PARENT_ID") })
    @Id
    private Parent parent;

    /**. */

    @Column(name = "CHILD_ID")
    @Basic(fetch = FetchType.EAGER)
    @Id
    @GenericGenerator(name="child_seq",    strategy="com.DB2Dialect") 
    @GeneratedValue(generator="child_seq") 
    private Integer childId;

}

child entity goes like this:


public class Child implements Serializable {

    /** The Constant serialVersionUID. */
    private static final long serialVersionUID = 185670997643552301L;

    /** The pol cntct id. */
    @Column(name = "CHILD_ID")
    @Basic(fetch = FetchType.EAGER)
    @Id
    private Integer childId;

    @ManyToOne(cascade = { CascadeType.ALL }, fetch = FetchType.LAZY)
    @JoinColumns( { @JoinColumn(name = "PARENT_ID", referencedColumnName = "PARENT_ID") })
    @Id
    private Parent parent;

}

Java代码

   ...................
    ..............
    parent.getChild().clear();
    Child child = new Child(); 
    parent.setChild(child);

这里可能有什么问题。
提前致谢...

Answer 1

您的最后一段 Java 代码无法编译。我想它看起来像

parent.getChilds().clear(); // note: you should name it children rather than childs
parent.setChilds(someNewSetOfChildren):

不要做最后一条指令。不是用另一个替换集合，而是清除集合并将新的 child 添加到清除的集合中:

parent.clearChildren();
parent.addChildren(someNewSetOfChildren);

其中方法定义为:

public void clearChildren() {
    this.children.clear();
}

public void addChildren(Collection<Child> children) {
    this.children.addAll(children);
}

setChildren 方法应该完全删除，或者应该用以下实现替换:

public void setChildren(Collection<Child> children) {
    this.children.clear();
    this.children.addAll(children);
}