Hibernate JPA：如何删除单向多对多关系中的链接记录？

我有实体“活动”和“发票”的单向多对多映射。映射仅在活动实体中设置（我不需要从发票端访问活动）

当我运行这些代码时，我认为em将首先从联接表中删除记录，然后删除活动记录（发票记录应保持不变）。但是联接表中的记录从未被删除。我收到此外键错误：

[STDOUT] Hibernate: delete from OP_ACTIVITY where OBJECT_ID=?
[JDBCExceptionReporter] SQL Error: 1451, SQLState: 23000 
ERROR [JDBCExceptionReporter] Cannot delete or update a parent row: a foreign key constraint fails (`prod/op_activity_invoice_xref`.......

我做错了什么？请帮忙，谢谢。

我想你需要

@manytomy（cascade={CascadeType.REMOVE}）

选项

CascadeType.REMOVE：删除实体时，也删除实体 在这个领域举行

在活动中：

@ManyToMany(cascade = {CascadeType.REMOVE})
@JoinTable(name = "OP_ACTIVITY_INVOICE_XREF", joinColumns = @JoinColumn(name = "ACTIVITY_ID",  referencedColumnName = "OBJECT_ID"), inverseJoinColumns = @JoinColumn(name = "INVOICE_ID", referencedColumnName = "OBJECT_ID"))
private Set<Invoice> invoices;

或者，您可以在@PreRemove添加注释： 将以下方法添加到不是关系所有者的实体（发票）

---

尝试添加cascadeType.remove选项，但没有区别。它不会删除链接记录，因此我仍然会收到相同的错误。感谢您的帮助，我发现我的问题与其他问题有关。这是删除链接记录的正确方法（如我前面所说，我不想删除发票）：

activity.getInvoices（）.clear（）；em.remove（活动）
[STDOUT] Hibernate: delete from OP_ACTIVITY where OBJECT_ID=?
[JDBCExceptionReporter] SQL Error: 1451, SQLState: 23000 
ERROR [JDBCExceptionReporter] Cannot delete or update a parent row: a foreign key constraint fails (`prod/op_activity_invoice_xref`.......

@ManyToMany(cascade = {CascadeType.REMOVE})
@JoinTable(name = "OP_ACTIVITY_INVOICE_XREF", joinColumns = @JoinColumn(name = "ACTIVITY_ID",  referencedColumnName = "OBJECT_ID"), inverseJoinColumns = @JoinColumn(name = "INVOICE_ID", referencedColumnName = "OBJECT_ID"))
private Set<Invoice> invoices;

for (Invoice invoice : activity.getInvoices()) {
   em.remove(invoice);
}
activity.getInvoices().clear();
em.remove(activity);
... flush() etc...

@PreRemove
private void removeInvoicesFromActivities() {
    for (Activity a : activities) {
        a.getInvoices().remove(this);
    }
}