JPA 在保存 OneToMany 关系时不清除 Set 迭代器

Question

我有一个基本的 Spring 启动应用程序。使用 Spring 初始化程序、JPA、嵌入式 Tomcat、Thymeleaf 模板引擎，并将其打包为可执行 JAR 文件。

我有这个域名class:

    Entity
    @DiscriminatorValue("sebloc")
    public class SeblocDevice extends Device {

        /**
         * 
         */
        private static final long serialVersionUID = 1L;


        public SeblocDevice() {
            super();
        }

        public SeblocDevice(String deviceKey, String devicePAC) {
            super(deviceKey, devicePAC);
        }

        @OneToMany(mappedBy = "device", cascade = CascadeType.ALL, fetch = FetchType.EAGER, orphanRemoval = true)
        private Set<DeviceDriver> driverDevices = new HashSet<>();

        public Set<DeviceDriver> getDriverDevices() {
            return driverDevices;
        }

        public void setDriverDevices(Set<DeviceDriver> driverDevices) {
            this.driverDevices = driverDevices;
        }

      public void clearDriverDevices()  {
    for (DeviceDriver deviceDriver : deviceDrivers) {
        deviceDriver.setDriver(null);
        driverDevices.remove(deviceDriver);
    }

public void removeDriverDevice(DeviceDriver deviceDriver)  {
    deviceDriver.setDriver(null);
    driverDevices.remove(deviceDriver);
}
}
    ...
    }

和另一个域 object

@Entity
@Table(name = "t_device_driver")
public class DeviceDriver implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    public DeviceDriver() {

    }

    public DeviceDriver (SeblocDevice device, Driver driver) {
        this.device = device;
        this.driver = driver;
    }


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

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "device_id")
    private SeblocDevice device;

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "driver_id")
    private Driver driver;

    public SeblocDevice getDevice() {
        return device;
    }

    public void setDevice(SeblocDevice device) {
        this.device = device;
    }

    public Driver getDriver() {
        return driver;
    }

    public void setDriver(Driver driver) {
        this.driver = driver;
    }
}

和这个 JUnit 测试，在上次测试中我排除了 1 driver 但我得到了 2（清除所有 driver 并添加 1）

    @Test
    public void testUpdateAuthorizedDriver() {

        SeblocDevice seblocDevice = (SeblocDevice) deviceService.findById((long)1);

        assertEquals (1,seblocDevice.getDriverDevices().size());

        Driver authorizedDriver   = (Driver) driverService.findById((long)2);

        DeviceDriver dd  = new DeviceDriver (seblocDevice, authorizedDriver);

DeviceDriver ddToRemove = seblocDevice.getDeviceDrivers().iterator().next();

        seblocDevice.removeDriverDevice(ddToRemove);

        seblocDevice.clearDriverDevices()
        seblocDevice.getDriverDevices().clear();
        seblocDevice.getDriverDevices().add(dd);

        deviceService.save(seblocDevice);

        assertEquals (1,    seblocDevice.getDriverDevices().size());
        assertEquals (1,    Iterators.size(deviceService.findSeblocDeviceAll().iterator()));

        SeblocDevice seblocDeviceRetrieved  = deviceService.findSeblocDeviceAll().iterator().next();

        assertEquals (1,    seblocDeviceRetrieved.getDriverDevices().size());

    }

我也试过在服务级别创建一个方法

public interface DeviceDriverRepository extends CrudRepository<DeviceDriver, Long> {

}
@Transactional
     public SeblocDevice cleanDrivers (SeblocDevice seblocDevice) {
         deviceDriverRepository.delete(seblocDevice.getDeviceDrivers());
     seblocDevice.getDeviceDrivers().clear();
     seblocDevice.setDeviceDrivers(null);
     return seblocDeviceRepository.save (seblocDevice);
     }

然后是deviceService.cleanDrivers(seblocDevice);

但是 driver 又出现了

Answer 1

crizzis 是对的，您必须将设备设置为 null。

保持双向关联一致的最佳方法是创建方便的方法，例如：

public void addDriverDevice(DeviceDriver deviceDriver)  {
    deviceDriver.setDriver(deviceDriver);
    driverDevices.add(deviceDriver);
}

public void removeDriverDevice(DeviceDriver deviceDriver)  {
    deviceDriver.setDriver(null);
    driverDevices.remove(deviceDriver);
}

如果你想全部清除

public void clearDriverDevices()  {
    for (DeviceDriver deviceDriver : deviceDrivers) {
        deviceDriver.setDriver(null);
        driverDevices.remove(deviceDriver);
    }
}

Answer 2

为了让您的代码按预期工作，您需要在 SeblocDevice.driverDevices 属性的 @OneToMany 关系中添加 orphanRemoval=true 参数，如下所示：

@OneToMany(mappedBy = "device", cascade = CascadeType.ALL, fetch = FetchType.EAGER, orphanRemoval = true)
    private Set<DeviceDriver> driverDevices = new HashSet<>();

清楚地了解JPA映射。你需要记住，在一段关系中，总是有主人的一面。例如，在 @OneToMany 与 @ManyToOne 关系中，@ManyToOne 是所有者，因为它引用了另一个实体。

基本上，实体管理器只关心所有者端的更改，即如果您调用 DeviceDriver.setDevice(null)，将执行删除。但恰恰相反 (SeblocDevice.getDriverDevices().clear()) 不正确。

为此，有orphanRemoval参数，这是不言自明的。分配此参数后，实体管理器现在将作为所有者控制集合的元素，SeblocDevice.getDriverDevices().clear() 将删除数据库中不在 SeblocDevice.getDriverDevices 集合中的 DeviceDrivers，即使 DeviceDriver.device 不为空。

JPA 在保存 OneToMany 关系时不清除 Set 迭代器

JPA not clearing a Set iterator when saving in OneToMany relationship

java

spring

persistence

jpa

javax