Spring JPA ManyToOne - 在刷新之前保存瞬态实例

Question

I created a Spring Web Application with database access. I have a class Person - which has references to a class Address . A person has an address as well as the company, so person and company both refer to the Address table. I did this by defining a @ManyToOne relation from person to address as well as the company.

    @ManyToOne
    @JoinColumn (name="COMPANY_ID")
    private Adress companyId;

    @ManyToOne
    @JoinColumn (name="SUBSIDIARY_ID")
    private Adress subsidiaryId;

In the person repository I have a save method like this:

 public Person save(Person entity) {

    SaveAccess<Person> ao = createSaveAccess();

    ao.setEntity(entity);
    ao.execute();
    return ao.getResult();
}

The thing is, if I try to add a new person I get a Hibernate-TransientPropertyValueException which says Object references an unsaved transient instance - save the transient instance before flushing. Can anyone help me here?

Answer 1

Can you try this

@ManyToOne(cascade = CascadeType.ALL)

    @JoinColumn (name="COMPANY_ID")
    private Adress companyId;

   @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn (name="SUBSIDIARY_ID")
    private Adress subsidiaryId;

reference: Hibernate TransientPropertyValueException When saving data

https://dzone.com/tutorials/java/hibernate/hibernate-example/hibernate-mapping-many-to-one-using-annotations-1.html

Answer 2

I had a similar issue with a @OneToOne annotation of a table called Product to another one called Category . I wanted to specify that every Product has to have a single Category .

Thus, I had to make sure to set the cascade type to be CascadeType.ALL like so:

@OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
@JoinColumn(name = "CATEGORY_NAME")
private Category category;

Answer 3

I don't think so the address contains so much data it justifiable to store as an independent entity. For performance considerations I recommend you to use embeddable + embedded classes for this purpose:

@Embeddable
public class Address
{
  String number;
  String street;
  String city;
  String country;
}

@Entity
public class Person
{
  @Id
  protected long id
  ...
  @Embedded
  Address address;
  @Embedded
  Address companyAddress;
  ...
}

If you have a legacy system and you have to store the addresses in a separate table, there is the @SecondaryTable solution:

@Entity
@Table(name = "EMPLOYEE")
@SecondaryTable(name = "ADDRESS", pkJoinColumns = @PrimaryKeyJoinColumn(name = "EMPLOYEE_ID"))
public class Employee
{
    //...
    @Column(table = "ADDRESS")
    private Address address;

    @Column(table = "ADDRESS")
    private Address companyAddress;
}