Develop Reference

Nested entities contains null after save

I have an entity with some nested entities like this
public class MyEntity {
#ManyToOne
#JoinColumn(name="FK_ENTITY2")
private Entity2 fkEntity2;
#ManyToOne
#JoinColumn(name="FK_ENTITY3")
private Entity3 fkEntity3;
}
with entity2 and entity3 like this:
public class Entity2/3{
#Id
private Long id;
#Column(name = "code")
private String code;
#Column(name = "desc")
private String desc;
//getter and setter etc
}
Both Entity2 and Entity3 have values stored in the database so when I'm doing an insert on MyEntity, I'm doing this:
#Transactional
#Service
public MyService {
//idFromController and otherIdFromController refers to existent records in the database
public MyDto save(Long idFromController, Long otherIdFromController){
Entity2 entity2 = new Entity2();
entity2.setId(idFromController);
Entity3 entity3 = new Entity3();
entity3.setId(otherIdFromController);
MyEntity newMyEntity = new MyEntity();
newMyEntity.setEntity2(entity2);
newMyEntity.setEntity3(entity3);
MyEntity result = myEntityRepository.saveAndFlush(newMyEntity);
return getDto(result);
}
}
it works fine, the data are stored correctly in the DB with the correct foreign keys BUT...
After insert I want to build a DTO which contains id, code and desc from the nested entities so something like this:
private MyDto getDto(MyEntity result){
MyDto dto = new MyDto();
dto.setId2(result.getEntity2().getId());
dto.setCode2(result.getEntity2().getCode());
dto.setDesc2(result.getEntity2().getDesc());
dto.setId3(result.getEntity3().getId());
dto.setCode3(result.getEntity3().getCode());
dto.setDesc3(result.getEntity3().getDesc());
}
Here is the problem, I only got the id fields and null on code and description.
When I call getDto() in a search it works and every field has the correct values, so it is something related to the insert transaction? how could I solve this?

When you create the DTO, the (existing) entities are not attached to the persistence context, so the corresponding data has not been loaded from the DB and cannot be copied to the DTO.
One option would be to load the entities e.g. via 'myRepository.findById...' and associate the returned (managed) entities.

you missed some part of the many-to-one relation. first in MyEntity class it was better to define a fetch type. in Entity2 and Entity3 you need to define #OneToMany as the other side of the relation with declaration of fetch type and cascade = CascadeType.ALL which simply tells to hibernate what it can do with relative entity when you are doing save, delete ,update. I reformat your code as following
public class Entity2/3{
#Id
private Long id;
#Column(name = "code")
private String code;
#Column(name = "desc")
private String desc;
#OneToMany(cascade = CascadeType.ALL,mappedBy ="fkEntity2",fetch=FetchType.LAZY)
private List<Entity2> entityTwoList;
// for Entity3
#OneToMany(cascade = CascadeType.ALL,mappedBy ="fkEntity3",fetch=FetchType.LAZY)
private List<Entity3> entityThreeList;
public class MyEntity {
#ManyToOne(fetch=FetchType.LAZY)
#JoinColumn(name="FK_ENTITY2")
private Entity2 fkEntity2;
#ManyToOne(fetch=FetchType.LAZY)
#JoinColumn(name="FK_ENTITY3")
private Entity3 fkEntity3;
}
}

returning a list of instances by the foreign key

I have two models, Owner and Contract. A contract has an instance of an owner, owner does not have a list of contracts. I'm trying to query my list of contracts, to return a list filtered by owner, ie, a list of contracts by owner.
I had tried to follow previous examples and use Criteria to write a custom query, but, following suggestions I've checked the docks and tried to use named queries instead, however, I'm still really struggling.
There was an unexpected error (type=Internal Server Error, status=500).
Named parameter not bound : ownerId; nested exception is org.hibernate.QueryException: Named parameter not bound : ownerId
My models look like this:
#Entity
#Table(name="Contracts")
#NamedQueries({
#NamedQuery(
name = "Contract.allContractsByOwner",
query = "SELECT c FROM Contract c WHERE c.owner.id LIKE :ownerId"
)
})
public class Contract {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column
private Long id;
#ManyToOne
private Owner owner;
#Column
private double price;
#Column
private String deliverDate;
public Contract(Owner owner, double price, String deliverDate) {
this.id = id;
this.owner = owner;
this.price = price;
this.deliverDate = deliverDate;
}
and
#Entity
#Table(name="Owners")
public class Owner {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column
private Long id;
#Column
private String name;
public Owner(String name){
this.name = name;
}
my contractRepoImpl
#Service
public class ContractRepositoryImpl implements ContractRepositoryCustom {
ContractRepository contractRepository;
#Autowired
EntityManager entityManager;
public List allContractsByOwner(Long ownerId) {
List contracts = entityManager.createQuery(
"SELECT c FROM Contract c WHERE c.owner.id LIKE :ownerId", Contract.class)
.getResultList();
return contracts;
}
}
which I name in my ContractRepo and ContractRepoCustom files, and then in my controller I map to it like so. But, when I query it in my browser I get the error in my terminal.
#GetMapping(value="/owners/{ownerId}/contracts")
public List allContractsByOwner(#PathVariable("ownerId") Long ownerId){
return contractRepository.allContractsByOwner(ownerId);
}
I appreciate this is probably beginners mistakes, I am trying to follow docs but get a bit stuck with syntax & where annotations need to go.

Thanks JB Nizet, got there in the end
I added parameters to my contractRepoImpl
#Service
public class ContractRepositoryImpl implements ContractRepositoryCustom {
ContractRepository contractRepository;
#Autowired
EntityManager entityManager;
public List allContractsByOwner(Long id) {
List contracts = entityManager.createQuery(
"SELECT c FROM Contract c WHERE c.owner.id = :ownerId", Contract.class)
.setParameter("ownerId", id)
.getResultList();
return contracts;
}
}
that then produced a SQL error, which I fixed by changing my #NamedQuery from 'LIKE' to '=' in my Contract class...
#NamedQueries({
#NamedQuery(
name = "Contract.allContractsByOwner",
query = "SELECT c FROM Contract c WHERE c.owner.id = :ownerId"
)
})

How to get Entity based on member object's field value rather than member objects ID

I have three classes and code for the same is displayed below
Enquiry Class:
#Entity
public class Enquiry
{
#Id
#GeneratedValue
private int id;
private String name;
private String discription;
private int status;
#Temporal(TemporalType.DATE)
private Date enquiryDate;
}
User Class:
#Entity
public class User
{
#Id
#GeneratedValue
private int id;
private String name;
private String userId;
private String password;
}
UserEnquiryUserEnquiryMapping Class:
#Entity
public class UserEnquiryMapping
{
#Id
#GeneratedValue
private int id;
#ManyToOne
private User user;
#ManyToOne
private Enquiry enquiry;
}
Now suppose if we want to get Enquiry(s) for a particular User than we can easily get it by passing a User object and hibernate will generate query by using id field from User object, and code for the same scenario is mentioned below.
EntityManager entityManager = session.getEntityManagerFactory().createEntityManager();
CriteriaBuilder builder = entityManager.getCriteriaBuilder();
CriteriaQuery<UserEnquiryMapping> criteria = builder.createQuery(UserEnquiryMapping.class);
Root<UserEnquiryMapping> root = criteria.from(UserEnquiryMapping.class);
criteria.select(root);
criteria.where(builder.equal(root.get("user"), user));
userEnquiries = entityManager.createQuery(criteria).getResultList();
But my requirement is I want to get User enquiries on the basis of user's name or we can say that I want to generate query like this
Select * from UserEnquiryMapping inner join Enquiry on UserEnquiryMapping.Enquiry_ID = Enquiry.ID inner join User on UserEnquiryMapping.User_ID = User.ID where User.name="Test";
How can I do this?

builder.equal(root.get("user").get("name"),user.getName());
glad it help you!

Hibernate mapping of internationalized database

I want to get international content from database based on locale provided in hibernate query. This is a question about hibernate mapping but please feel free to propose better database design if mine is wrong.
My DB design (simplified):
db design
So I have table with non translatable data and additional table with translated content but with additional field "locale" for distinction of language.
My java classes looks like this:
public class Car {
private Long id;
private Long length;
private Long weight;
private CarTranslated carTranslated;
// getters and setters
public class CarTranslated {
private Long id;
private Long carId;
private String desc;
// getters and setters
I want to be able to get one car with single query. With regular jdbc I would use something like this sql query:
public Car getById(Long id, Locale locale) {
Car c = new Car();
String sql = "select c.car_id, c.length, c.weight, ct.id, ct.descryption,
ct.car_id as "Translated car_id" from car c join car_translated ct on
(c.car_id = ct.car_id) where c.car_id ="+ id+" and ct.locale ='"+locale+"'";
// code to set fields of the object using ResultSet
return c;
}
What would be a hibernate annotation mapping and query for this setup? I tried several attempts but to no avail. Currently my best attempt was as below:
Mapping:
#Entity
#Table(name="CAR")
public class Car {
#Id
#Column(name="car_id")
private Long carId;
#Column (name="weight")
private Long carWeight;
#Column (name="length")
private Long carLength;
#OneToOne(cascade = CascadeType.ALL)
#JoinColumn(name ="CAR_ID")
private CarTranslated localized;
// getters and setters
#Entity
#Table(name="CAR_TRANSLATED")
public class CarTranslated {
#Id
#Column (name="id")
private Long id;
#Column (name="car_id")
private Long carId;
#Column (name="descryption")
private String desc;
#Column(name="locale")
private Locale locale;
DAO:
public Car getCarById(Locale locale, Long id) {
Car car = new Car();
try {
Session session = HibernateUtils.getSessionFactory().openSession();
Criteria cr = session.createCriteria(Car.class)
.add(Restrictions.eq("carId", id));
Criteria cr1 = session.createCriteria(CarTranslated.class)
.add(Restrictions.eq("locale", locale));
car = (Car) cr.uniqueResult();
car.setLocalized((CarTranslated) cr1.uniqueResult());
} catch (Exception e) {
System.out.println(e.getMessage());
}
return car;
}
This is a work-around and I'm wondering what would be a proper way to do this?

You should have an annotation on both columns when mapping to a FK. (JavaDoc)

org.hibernate.ObjectNotFoundException issue with using list()

The following query throws the exception:
Query query = session.createQuery("from Associate as a order by a.username asc");
associates = query.list();
org.hibernate.ObjectNotFoundException: No row with the given identifier exists: [ca.mypkg.model.Associate#0]
If I create an entry in the database with id of 0 it works just fine. I don't really get it because I'm just trying to load all the entries in the db not just a specific one.
Similar questions I've found have been concerned with trying to load an object with a given ID I'm doing no such thing.
Associate class:
#Table(name = "user")
#XmlRootElement(name = "associate")
public class Associate implements Serializable {
private String username;
private String password;
private String firstName;
private String lastName;
private String userType;
private int id;
private String email;
private String isActive;
private Department dept;
private String lastUpdated;
private String associate_type;
// ...
#Id
#GeneratedValue
public int getId() {
return id;
}
#OneToOne
#JoinColumn(name = "dept")
public Department getDept() {
return dept;
}

From my experience this type of error message usually means it does not find joined entity by mentioned id, and not the entity requested in the query (Associate, in your case).
My guess is that Associate class contains a join entity which has primitive type primary key.