Question

如何将Spring Data JPA与Hibernate 5.0.12一起用作供应商，将现有数据库条目与非托管实体进行匹配？

说我有这样的实体：

@Entity
public class Person {

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

    private String name;

    @ManyToOne(cascade = CascadeType.ALL)
    private Address address;
}

@Entity
public class Address {

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

    @Column(unique = true)
    private Integer zip;
    private String city;
}

@Repository
public interface PersonRepository extends JpaRepository<Person, Integer> {
    // implementation provided by Spring Data JPA
}

实例源自JAXB unmarshaller，出于我们的目的，我们假设：

public Person data(String name, Integer zip, String city) {
    Person person = new Person();
    person.setName(name);

    Address address = new Address();
    address.setZip(zip);
    address.setCity(city);

    person.setAddress(address);

    return person;
}

现在我希望此代码能够按上述方式工作：

Person p1 = data("Alice", 12345, "Berlin");
Person p2 = data("Bob", 12345, "Berlin");

// create a row in person table and create a row in address table
personRepository.save(p1);

// this should only create a row in person 
// and assign existing address entity reference to it
personRepository.save(p2);

当然，代码因唯一约束违规而失败，所以我想知道是否有某种方式我可以为JPA指定业务键，以便将我的实体与现有的行匹配数据库（例如zip）。

使用Spring Data JPA查找匹配实体进行级联

0 个答案: