如何避免使用 JPA - 编程之家

如何解决如何避免使用 JPA

@Entity
@Table(name = "PERSISTENCE_USER")

    public class User implements Serializable {
        // HERE IS A SNIPPET
        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
    
        private Long id;
        @NotNull
        private String firstName;
        @NotNull
        private String lastName;
        ................
    }
@Entity
@Table(name = "PERSISTENCE_ORDER")
@NamedQueries({
    @NamedQuery(
            name = "findAllorders",query = "SELECT o FROM CustomerOrder o"
    ),@NamedQuery(
            name = "deleteall",query = "DELETE FROM CustomerOrder"
    )
})

    public class CustomerOrder implements Serializable {
    
        //HERE IS A SNIPPET
        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        private Long id;
        @NotNull
        String status;
        @NotNull
        @OnetoMany(cascade = CascadeType.ALL,orphanRemoval = true)
        private List<LineItem> lineItems;
        @NotNull
        @ManyToOne
        private User customer;
        ...........
    }

当我尝试删除与 User 实体具有单向 @ManyToOne 的 CustomerOrder 实体时，出现以下错误：

Internal Exception: org.apache.derby.shared.common.error.DerbysqlIntegrityConstraintViolationException: DELETE on table 'PERSISTENCE_ORDER' caused a violation of foreign key constraint 'PRSSTNCSRPRSSRDRSD' for key (21).  The statement has been rolled back.
Error Code: 20000
Call: DELETE FROM PERSISTENCE_ORDER
Query: DeleteallQuery(name="deleteall" referenceClass=CustomerOrder sql="DELETE FROM PERSISTENCE_ORDER")
    at org.eclipse.persistence.exceptions.DatabaseException.sqlException(DatabaseException.java:331)
    at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeDirectNoSelect(DatabaseAccessor.java:905)
    at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeNoSelect(DatabaseAccessor.java:967)
        ............................................................................
        ............................................................................
Caused by: org.apache.derby.shared.common.error.DerbysqlIntegrityConstraintViolationException: DELETE on table 'PERSISTENCE_ORDER' caused a violation of foreign key constraint 'PRSSTNCSRPRSSRDRSD' for key (21).  The statement has been rolled back.

之后，我尝试先删除 User 实体，然后再删除 CustomerOrder 实体，但这没有任何区别。我应该如何定义实体关系映射以避免此错误？

谢谢

PS：我在 Windows 10 64 位和 Apache Derby DB 上使用带有 EclipseLink 的 Glassfish 5.1

解决方法

当发出“DELETE FROM CustomerOrder”批量删除查询时，JPA 不会为您做任何事情 - 它完全按照 JPQL 的要求发出 SQL - 因此由您通过清空或删除任何引用来维护到要删除的行，然后再删除。

异常本身表明违反了 FK 约束“PRSSTNCSRPRRSSRDRSD”，可以在数据库中找到该约束以准确告诉您是哪个关系导致了问题。查看 CustomerOrder 实体，lineItems 集合的映射方式是将外键放入 LineItems 表中，这需要在删除成功之前清除这些行。