JPA-从参考表中删除条目

Question

我实现了具有组和权限的工作台权限系统。 引用表workbench_group_permissions_reference具有引用，因此我可以轻松地添加和删除组的权限。 添加新的参考条目可以正常工作，但删除则不能。 我没有收到任何错误，但是删除后引用仍然存在于数据库中。 我正在使用postgreSQL。

这是我的参考班：

@XmlRootElement
@Entity
@Table(name = "workbench_group_permissions_reference", uniqueConstraints = {
        @UniqueConstraint(columnNames = { "workbenchgroupspermissions_id", "workbench_groups_id" }) })
public class WorkbenchGroupPermissionReferenceEntity extends BasicEntity {

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

    @ManyToOne
    @JoinColumn(name = "workbenchgroupspermissions_id")
    private WorkbenchPermissionEntity workbenchPermission;

    @ManyToOne
    @JoinColumn(name = "workbench_groups_id")
    private WorkbenchGroupEntity workbenchGroup;

    /**
     * Empty constructor to make JPA happy.
     */
    public WorkbenchGroupPermissionReferenceEntity() {
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public WorkbenchPermissionEntity getWorkbenchPermission() {
        return workbenchPermission;
    }

    public void setWorkbenchPermission(WorkbenchPermissionEntity workbenchPermission) {
        this.workbenchPermission = workbenchPermission;
    }

    public WorkbenchGroupEntity getWorkbenchGroup() {
        return workbenchGroup;
    }

    public void setWorkbenchGroup(WorkbenchGroupEntity workbenchGroup) {
        this.workbenchGroup = workbenchGroup;
    }
}

这是我的删除方法：

public void deleteWorkbenchGroupPermission(final WorkbenchGroupPermissionReferenceEntity workbenchGroupPermission) {
    long id = workbenchGroupPermission.getId();
    super.delete(WorkbenchGroupPermissionReferenceEntity.class, id);
}

和super.delete方法：

protected void delete(final Class<?> type, final Object id) {
    Object ref = this.em.getReference(type, id);
    this.em.remove(ref);
}

我在这里想念什么？

Answer 1

Dragan 评论中的链接为我指明了正确的方向。 我试图删除该引用，但是所属实体（WorkbenchGroupEntity）仍然具有该引用。 我要解决的问题是首先从拥有实体中删除引用，然后再删除交叉引用实体：

    WorkbenchGroupPermissionReferenceEntity permissionToRemove = new WorkbenchGroupPermissionReferenceEntity();
    for(WorkbenchGroupPermissionReferenceEntity permissionReference : existingGroupPermissions) {
        Long permissionRefernceId = permissionReference.getId();
        if(permissionRefernceId.equals(permissionId)){
            permissionToRemove = permissionReference;
        } else {
            newGroupPermissions.add(permissionReference);
        }
    }
    workbenchGroupEntity.setWorkbenchGroupPermissions(newGroupPermissions);
    workbenchGroupControl.updateWorkbenchGroup(workbenchGroupEntity);
    workbenchGroupPermissionsControl.deleteWorkbenchGroupPermission(permissionToRemove);

编辑：由于上述解决方案是删除无法正常工作的主要原因，所以我犯了另一个愚蠢的错误：我正在将交叉引用实体的ID与许可ID的ID进行比较，而不是许可ID本身的ID，因此从未找到参考。

更新检查：

    for (WorkbenchGroupPermissionReferenceEntity permissionReference : existingGroupPermissions) {
        // here was the mistake
        Long permissionReferenceId = permissionReference.getWorkbenchPermission().getId();
        if (permissionReferenceId.equals(permissionId)) {
            permissionToRemove = permissionReference;
        } else {
            newGroupPermissions.add(permissionReference);
        }
    }