Spring Data Rest Left Outer Join non-Entity POJO Null Entity Error - sql

Question

How do i accomplish getting the this interface method to work? i am using a MySQL DB if that matters...
public interface PersonRoleRepository extends CrudRepository<PersonRole,Long>{
//This causes null entity error from hibernate even though the SQL works outside hibernate
#Query(value="select * from Role r left outer join Person_Role pr on r.id = pr.role_id and pr.person_id = ? order by pr.expires_date desc", nativeQuery = true)
List<PersonRoleDto> getAllRolesAndPersonsStatusWithEachRole(int personId);
}
Here is the SQL query that returns what i want in SQL Workbench...
Select r.*, pr.*
from
Role r
left outer join person_role pr on r.id = pr.role_id and pr.person_id = ?
order by pr.expires_date desc;
Important MySQL database structure...
Table: Role
role_id bigint
name varchar
description varchar
...
Table: Person
person_id bigint
first_name varchar
last_name varchar
...
Table Person_Role_Link
person_role_id bigint
role_id bigint
person_id bigint
...
alter table person_Role_Link add constraint l1 foreign key (person_id) references Person(person_id)
alter table person_Role_Link add constraint l2 foreign key (role_id) references Role(role_id)
Here is the entity info...
#Entity
#Table(name="Role")
#EntityListeners(AuditEntityListener.class)
public class Role extends AbstractAuditEntity {
private static final long serialVersionUID= 44543543543543454543543L;
#id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(name="role_id")
private long id;
#NotNull
private String fullName
...
#OneToMany(mappedBy="role",cascade=CascadeType.ALL)
private Set<PersonRole> personRoles = new HashSet<>();
...
}
#Entity
#Table(name="Person_Role_Link")
#EntityListeners(AuditEntityListener.class)
class PersonRole extends AbstractAuditEntry{
private static final long serialVersion = 54324243242432423L;
#id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(name="person_role_id")
private long id;
#ManyToOne
#JoinColumn(name="person_id")
private Person person;
#ManyToOne
#JoinColumn(name="role_id")
private Role role;
...
}
#Entity
#Table(name="Person")
#EntityListeners(AuditEntityListener.class)
public class Person extends AbstractAuditEntity{
private ... serialVersionUID...;
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(name="person_id")
private Long id;
...
#OneToMany(mappedBy="person", cascade=CascadeType.ALL)
private Set<PersonRole> personRoles = new HashSet<>();
...
}
Just for now i made a simple interface...
public interface PersonRoleDto {
String getFullName();
String getDescription();
//i want more attributes but for now i will just see if it works with the basics
}
Here is the latest HQL i tried...
public interface PersonRoleRepository extends CrudRepository<PersonRole,Long>{
//PersistentEntity must not be null
#Query("select r.fullName as fullName, r.description as description from Role r left join r.personRoles pr where pr.person = :person")
List<PersonRoleDto> findAllRolesWithPersonsStatus(#Param("person") Person person);
...
}
Whether I use HQL or native SQL i get a null entity error from hibernate. Also, the SQL generated from the HQL works without error but i still get a null entity error in code and, second, the SQL generated from HQL is slightly off which makes the results off. That's why i was trying so hard to get the native SQL to work.
The relationship is used to figure out how many people are in a role and at other times what roles a person has. This is a circular relationship, i'd say. I work on an Intranet so i had to hand type everything. If there are any problems seen in my code other than with the stated native query as stated then it is most likely because i had to hand type everything and not because the code is buggy. Everything else works so far but this one thing.
All help is appreciated.
UPDATE!!!!
I think this is the answer to my problem but when i try it i still get the error: PersistentEntity must not be null!
Here is how i tried to set it up...
//Added this to the top of PersonRole entity
#SqlResultSetMapping(
name="allRolesAndPersonsStatusWithEachRole"
classes={
#ConstructorResult(
targetClass=PersonRoleStatus.class,
columns={
#ColumnResult(name="full_name"),
#ColumnResult(name="description"),
...
}
)
}
)
#NamedNativeQuery(name="PersonRole.getAllRolesAndPersonsStatusWithEachRole",
query="Select r.*, pr.* from Role r Left Join person_role_link on r.role_id = pr.role_id and pr.person_id = :id", resultSetMapping="allRolesAndPersonsStatusWithEachRole")
Created my DTO like this...
public class RolePersonStatus {
private String fullName;
private String description;
private String ...
public RolePersonStatus(String fullName, String description, ...){
this.fullName = fullName;
this.description = description;
...
}
}
In my repository i just have:
//No annotation because it stated that the name of the method just needed to match the native query name?!?!?
List<RolePersonStatus> findAllRolesWithPersonStatus(#Param("id" Long id);
What am i missing???????

Answer 1

Try this way:
Entities
#Entity
#Table(name = "parents")
public class Parent {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String name;
#OneToMany
private List<Child> children = new ArrayList<>();
//...
}
#Entity
#Table(name = "children")
public class Child {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String name;
#ManyToOne(optional = false)
private Reference reference;
#OneToMany
private final List<Toy> toys = new ArrayList<>();
//...
}
#Entity
#Table(name = "references")
public class Reference {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String description;
//...
}
#Entity
#Table(name = "toys")
public class Toy {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String name;
//...
}
DTO
public interface DemoDto {
String getParentName();
String getChildName();
String getToyName();
String getDescription();
}
Repository
public interface ParentRepo extends JpaRepository<Parent, Long> {
#Query("select " +
"p.name as parentName, " +
"c.name as childName, " +
"t.name as toyName, " +
"r.description as description " +
"from " +
"Parent p " +
"join p.children c " +
"join c.reference r " +
"join c.toys t " +
"where c.id = ?1 " +
"order by r.description desc")
List<DemoDto> getDto(Long childId);
}
Usage
#RunWith(SpringRunner.class)
#SpringBootTest
public class ParentRepoTest {
#Autowired
private ParentRepo parentRepo;
#Test
public void getDto() throws Exception {
List<DemoDto> dtos = parentRepo.getDto(3L);
dtos.forEach(System.out::println);
}
}
Result
{parentName=parent2, toyName=Toy7, childName=child3, description=Description1}
{parentName=parent2, toyName=Toy8, childName=child3, description=Description1}
{parentName=parent2, toyName=Toy9, childName=child3, description=Description1}
More info is here.
Working example.