Question

我有一个Hibernate实体类代表＆＃34;设备＆＃34;表，链接到N deviceNetworks：

@Entity
    @Configurable  
    @Table(name = "device")
    public class Device implements Serializable
    {
        private static final long serialVersionUID = 1L;

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


        @Column(name = "device_name", nullable = false)
        private String deviceName;


        @OneToMany( cascade = {CascadeType.ALL}, fetch = FetchType.LAZY, 
                    mappedBy = "device_network", 
                    targetEntity = DeviceNetwork.class, orphanRemoval = true)
        private final Set<DeviceNetwork> deviceNetworks = Sets.newHashSet();

        ......

        public Set<DeviceNetwork> getDeviceNetworks()
        {
            return deviceNetworks;
        }

        public void addDeviceNetwork(final DeviceNetwork deviceNetwork)
        {
            deviceNetworks.add(deviceNetwork);
        }

        public void removeDeviceNetwork(final DeviceNetwork deviceNetwork)
        {
            deviceNetworks.remove(deviceNetwork);
        }
    }

和代表＆＃34; deviceNetwork＆＃34;的类：

@Entity
@Configurable
@Table(name = "device_network")
public class DeviceNetwork implements Serializable
{
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;
    @ManyToOne(targetEntity = Device.class)
    @JoinColumn(name="device_id", nullable=false)
    private Device device;
    @Column(name = "network_name", unique = true, nullable = false)
    private String networkName;
    ......
}

我有一个将新设备和新链接的deviceNetwork插入数据库的事务，然后我开始使用新的tranaction：

通过其ID检索新插入的设备;
添加新网络;
更新设备;

我使用EntityManager来完成此任务：

@Transactional
public void addNetworkToDevice(long deviceId, DeviceNetwork deviceNetwork)
{
    Device device = entityManager.get(deviceId); 

    device.addDeviceNetwork(deviceNetwork);

    entityManager.merge(device);
}

这会导致以下例外情况：

org.springframework.orm.jpa.JpaObjectRetrievalFailureException: 
Unable to find com.xxx.domain.DeviceNetwork with id 170; 
nested exception is javax.persistence.EntityNotFoundException: 
Unable to find com.xxx.domain.DeviceNetwork with id 170

id = 170应该是要插入的DeviceNetwork。似乎merge（）会尝试检索即将插入的deviceNetwork由其自动生成的ID，但未能这样做，因为它还没有被插入。

有趣的是，如果我在同一个交易中插入一个新设备和两个新的链接设备网络，它可以正常工作：

@Transactional
public void addDevice(Device device, DeviceNetwork deviceNetwork1, DeviceNetwork deviceNetwork2)
{
    Device deviceInDB = entityManager.get(device.getDeviceId());
    if deviceInDB == null)
    {
        entityManager.persist(device);
        deviceInDB = entityManager.get(device.getDeviceId());
    }

    deviceInDB.addDeviceNetwork(deviceNetwork1);
    deviceInDB.addDeviceNetwork(deviceNetwork2);

    entityManager.merge(deviceInDB);
}

有什么建议吗？

Answer 1

检查项目中提到的数据库用户是否可以访问表device_network

hibernate merge抛出EntityNotFoundException

1 个答案: