父级:StaffGroup
@Entity
@Table( name = "STAFF_GROUP")
public class StaffGroup implements Serializable{
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private long id;
@OneToMany(mappedBy="staffGroup", cascade = CascadeType.ALL)
private List<Staff> staffs = new ArrayList<>();
子项:员工
@Entity
@Table( name = "STAFF")
public class Staff implements java.io.Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
// Relationships
@ManyToOne
@JoinColumn(name = "STAFF_GROUP_ID")
private StaffGroup staffGroup;
这是一个使用 JPA 和 MySQL 作为数据库的 JavaFX 应用程序。
我为每个实体(staff 和 StaffGroup)都有一个 DAO。还有一个名为 StaffGate 的逻辑类,如下所示:
public class StaffGate {
// GRP
private List<StaffGroup> staffGrps = new ArrayList<>();
private StaffGroupDAO groupDAO = new StaffGroupDAO();
// Staff
private static List<Staff> staffList = new ArrayList<>();
private StaffDAO staffDao = new StaffDAO();
public void removeFromDBAndMemory(StaffGroup element) {
groupDAO.remove(element);
staffGrps.remove(element);
}
//...
现在,对于 View ,我有一个名为 StaffView 的类,该类是创建 View 的位置,并且它有两个 StaffGate 实例,一个用于 GroupStaff 操作,另一个用于 Staff。
public class StaffView {
private StaffGate staffGate = new StaffGate();// Grp operations
private StaffGate staffGatestf = new StaffGate();// Staff operations
现在,我可以创建一个组和员工,并且它们会被持久化,我也可以删除员工实体。问题是当我想删除 StaffGroup 实体时,它会抛出 FK 违规异常
[EL Warning]: 2016-06-25 10:35:20.567--UnitOfWork(1053875258)--Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.6.2.v20151217-774c696): 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 (`school-finma`.`staff`, CONSTRAINT `FK_STAFF_STAFF_GROUP_ID` FOREIGN KEY (`STAFF_GROUP_ID`) REFERENCES `staff_group` (`ID`))
Error Code: 1451
Call: DELETE FROM STAFF_GROUP WHERE (ID = ?)
bind => [1 parameter bound]
Query: DeleteObjectQuery(StaffGroup [id=4, name=Drivers, imageByteInfoEntity=null, staffs={[]}, school=School [id=1, name=Banafsaj, schoolType=USA, address=null, creationDate=2016-06-13, image=ImageByteInfoEntity [id=1, byteImage.length=2793472, width=1024, height=682], active=true], active=true])
Exception in thread "JavaFX Application Thread" javax.persistence.PersistenceException: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.6.2.v20151217-774c696): 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 (`school-finma`.`staff`, CONSTRAINT `FK_STAFF_STAFF_GROUP_ID` FOREIGN KEY (`STAFF_GROUP_ID`) REFERENCES `staff_group` (`ID`))
Error Code: 1451
Call: DELETE FROM STAFF_GROUP WHERE (ID = ?)
bind => [1 parameter bound]
Query: DeleteObjectQuery(StaffGroup [id=4, name=Drivers, imageByteInfoEntity=null, staffs={[]}, school=School [id=1, name=Banafsaj, schoolType=USA, address=null, creationDate=2016-06-13, image=ImageByteInfoEntity [id=1, byteImage.length=2793472, width=1024, height=682], active=true], active=true])
at org.eclipse.persistence.internal.jpa.EntityManagerImpl.flush(EntityManagerImpl.java:879)
at derbyware.school.dao.AbstractFacade.remove(AbstractFacade.java:49)
at derbyware.school.logic.StaffGate.removeFromDBAndMemory(StaffGate.java:49)
我确实有cascade.all。
当我使用仅一个 StaffGate 实例时,该问题不会发生。
为什么会出现这种情况?我该如何解决它?
我在StaffGate中调用删除方法之前添加了这一行,但仍然是同样的问题:staffGatestf = new StaffGate();
更新
我的意思
And The problem does NOT occure when I use ONLY ONE StaffGate instance
是在类:StaffView 中我删除了:staffGatestf 实例,并且仅与 StaffGate 一起使用。在这种情况下不会发生异常。
最佳答案
我通过仅删除 StaffGate 的一个实例来修复此问题。但如果有人知道如何解决,我将不胜感激
关于java - JPA : weird Cascade delete behaviour, 一对多。使用两个单独的 DAO 时发生 FK 违规,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/38028591/