Question

这个问题可能看起来有点令人困惑，所以我会尝试用例子来表达。

我正在使用 JPA 2.0 和 Eclipselink 2.2

我有三个类人，学生和证书这两个关系：

学生从人

延伸

学生有证件（ @OneToOne ）

我的课程定义如下：

Person.java

@Entity
@Table(name = "person")
@Inheritance(strategy = InheritanceType.JOINED)
@DiscriminatorColumn(name = "type", discriminatorType = DiscriminatorType.STRING, length = 20)
@DiscriminatorValue("person")
public abstract class Person {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private String firstName;
    private String lastName;
    private String street;
    private String city;
    private String zipCode;
    private String phoneNumber;

    /*Getters and Setters*/

}

Student.java

@SuppressWarnings("serial")
@Entity
@Table(name = "student")
@DiscriminatorValue("student")
public class Student extends Person implements Serializable {

    @Column(unique = true)
    private String studentId;

    @OneToOne(fetch = FetchType.EAGER, cascade = { CascadeType.ALL }, orphanRemoval = true, optional = false, mappedBy = "student")
    @CascadeOnDelete
    private Credentials credentials;

    /*Getters and Setters*/
}

Credentials.java

@SuppressWarnings("serial")
@Entity
public class Credentials implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column(unique = true)
    private String username;

    private String password;

    private Student student;
}

问题在于，当我尝试删除学生

时

        entityManager.getTransaction().begin();
        entityManager.remove(student);
        entityManager.getTransaction().commit();

出现约束（我可以发布更多错误消息，但这似乎是关键）：

jul 26, 2013 11:51:50 AM com.vaadin.Application terminalError
Grave: Terminal error:
javax.persistence.PersistenceException: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.2.0.v20110202-r8913): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (`studentrecord`.`credentials`, CONSTRAINT `FK_CREDENTIALS_STUDENT_ID` FOREIGN KEY (`STUDENT_ID`) REFERENCES `person` (`ID`))
Error Code: 1451
Call: DELETE FROM person WHERE (ID = ?)
    bind => [36]
Query: DeleteObjectQuery(Alex)

我尝试过几次anotations，一个方向，学生和证书之间的双向关系，但结果总是相同。

如何删除学生实体？

任何帮助都会非常感谢，提前谢谢。

如何使用级联删除删除JPA中的继承类？

0 个答案: