jpa EntityManager-将查询结果映射到嵌套的dto类中

Question

public class User {
    private Long id;
    ...
    
    @ManyToOne
    private Address address
}

public class UserDTO {
    private Long id;
    private AddressDTO address;
    ...
}

Answer 1

您可以直接在JPQL中构造DTO。这里有一个例子。

select new your.package.UserDTO(u.id, a.country, a.city, a.street)
from User u join u.address a
where ...

这样的查询返回list 。

当然userdto必须有适当的构造函数：

public UserDTO(Long id, String country, String city, String street){
   this.id = id;
   this.address = new AddressDTO(country, city, street);
}