hibernate与master值一对一保存

Question

想要保存一个一对一的主值，如下所示。有一个address类，它包含一个city类一对一。但是city是我的主值，当我保存地址时我不想更新它。只需要从UI的下拉菜单中选择city并将对象设置为原来的地址并保存地址。但是当保存时getting below错误。

org.hibernate.transientPropertyValueException：对象引用了一个未保存的瞬态实例-在刷新之前保存瞬态实例:com.app.fd.entity.address.city->com.app.fd.entity.city

@Entity
public class Address extends BaseEntity implements Serializable {
/**
 * 
 */
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "CONTACT_SEQ_GEN")
@SequenceGenerator(name="CONTACT_SEQ_GEN", sequenceName = "CONTACT_SEQ", allocationSize=5)
@Column(name = "id", updatable = false, nullable = false)
private Long id;

@Size(max = 50)
@NotNull
private String address1;

@Size(max = 50)
private String address2;

@Size(max = 15)
@NotNull
private String state;

@Size(max = 10)
@NotNull
private String pin;

@Size(max = 255)
private String landmark;

private Boolean deleted;

@OneToOne()
@JoinColumn(name = "city_id", insertable=false,updatable=false)
private City city;

}


@Entity
public class City {

/**
 * 
 */

private static final long serialVersionUID = 1L;


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

@Size(max = 30)
@Column(name = "name",unique = true)
private String name;

@Size(max = 5)
@Column(name = "code",unique = true)
private String code;
}




repository.save(address); // TransientPropertyValueException error

Answer 1

出现此错误是因为您正在用未保存/分离的City实体保存Address实体。为了解决这个问题，您可以使用CascadeType.All，但在您的情况下，您不想修改city对象。您可以使用以下方法。

City cityFromUI = new City();
cityFromUI.setId(id); //get this id from UI. Store city dropdown as key = id and value = cityName
Address myNewAddress = new Address();
myNewAddress.set*()//Set other address fields
myNewAddress.setCity(cityFromUI);
repository.save(address);

使用上面的代码，您的地址将映射到相应的城市，并且您的城市不会更新，因为您在address实体中将updatable定义为false。