我有两个具有 OneToOne 关系的实体:
@Entity
@Table(name = "APPLICATION_DEVICE")
public class ApplicationDevice implements Serializable {
[...]
@Id
public ApplicationDeviceKey getApplicationDeviceKey()
{
return applicationDeviceKey;
}
@NotFound(action = NotFoundAction.IGNORE)
@OneToOne(cascade=CascadeType.ALL)
@JoinColumns( {
@JoinColumn(name = "applicationId", referencedColumnName = "applicationId",insertable=false,updatable=false, nullable = true),
@JoinColumn(name = "deviceId", referencedColumnName = "deviceId",insertable=false,updatable=false, nullable = true), }
)
public ApplicationDevicePushInfo getDevicePushInfo() {
return devicePushInfo;
}
和另一个实体:
@Entity
@Table(name = "APPLICATION_DEVICE_PUSHINFO")
public class ApplicationDevicePushInfo implements Serializable {
[...]
@Id
public ApplicationDeviceKey getApplicationDeviceKey()
{
return applicationDeviceKey;
}
@OneToOne
@JoinColumns( {
@JoinColumn(name = "applicationId", referencedColumnName = "applicationId",insertable=false,updatable=false, nullable = false),
@JoinColumn(name = "deviceId", referencedColumnName = "deviceId",insertable=false,updatable=false, nullable = false)}
)
public ApplicationDevice getApplicationDevice() {
return applicationDevice;
}
第二个实体可能为空,当我尝试存储我的第一个实体时,我得到:
Cannot add or update a child row: a foreign key constraint fails (`malcom_dev`.`application_device`, CONSTRAINT `FK16A0C0451DC7C799` FOREIGN KEY (`applicationId`, `deviceId`) REFERENCES `APPLICATION_DEVICE_PUSHINFO` (`applicationId`, `deviceId`))
默认情况下 nullable 为 true,所以我认为这种关系是可能的。
还有另一种方法可以让实体具有 oneToOne 关系而不创建新的列或表,并允许第二个实体为空?