在spring数据中保存父项时如何引用子项id

我有多对一的关系。 是否可以在保存父项之前根据特定列选择子项数据库id

这是我的密码：

public class Employee {
    @AssociationOverrides({@AssociationOverride(name = "staffNumber"), @AssociationOverride(name = "staffNumber"),
                           @AssociationOverride(name = "homeAddress", joinColumns = @JoinColumn(name = "homeAddress")),
                           @AssociationOverride(name = "officeAddress", joinColumns = @JoinColumn(name = "officeAddress"))})
    @EmbeddedId
    private EmployeeId id;
}

@Data
@Embeddable
public class EmployeeId {

    @Column(name = "staffNumber")
    private String staffNumber;

    @ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    private Address homeAddress;

    @ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    private Address officeAddress;

}

@Data
public class Address {
    @Id @GeneratedValue(strategy = GenerationType.AUTO)
    private int id;

    @Columnn(name="country")
    private String country;

    @Column(name="city")
    private String city;
}

public interface EmployeeRepository extends CrudRepository<Employee, EmployeeId> {}

无需选择

 addressRepository.findAddressByCity(city)

其中我只有一个没有id（id=0）的地址，但在数据库中有一个城市（“纽约”，id为2，“旧金山”，id为1）

---

您可以在不知道子主id的情况下保存子记录，但如果提取的不是主键列，请确保结果应该是唯一的

Employee employee = new Employee();
employee.setStaffNumber("123);

您可以通过其他列找到地址，如下所示

Address officeAddress = addressRepository.findAddressByCity(city); // Office Address
Address homeAddress = addressRepository.findAddressByCity(city); // Home Address

// Setting child objects in parent object
employee.setHomeAddress(homeAddress);
employee.setOfficeAddress(officeAddress);

最后，保存父对象，它将使用家庭和办公室地址保存员工详细信息

employeeRepository.save(employee);

---

是否要根据子表列名选择子表记录？请确切地指定所需的详细信息。我希望将父项与子项一起保存。我想做

employeeRepository.save（employee）不必首先在db中搜索地址id，结果如下``Employee:{EmployeeId:{staffNumber:“123”，homeAddress:id:2，-->2是地址表id officeAddress:id:1-->1是地址表id}“``你的意思是要用新地址保存新员工？请检查这是否可以在不知道孩子id的情况下保存孩子？但我知道一些孩子的专栏？谢谢Naresh。我希望我不必先做
findAddressByCity
来安排孩子们。我希望在Adress中有一些注释可以用来查询，可能类似于
@query（“从地址中选择id，城市=$”
Address officeAddress = addressRepository.findAddressByCity(city); // Office Address
Address homeAddress = addressRepository.findAddressByCity(city); // Home Address

// Setting child objects in parent object
employee.setHomeAddress(homeAddress);
employee.setOfficeAddress(officeAddress);

employeeRepository.save(employee);