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Trigger #OneToMany lazy fetch

I have an ExampleRequest entity that can optionally have one or more ExampleRequestYear. It's currently configured this way (unrelated fields and gettters/setters omitted for brevity, please let me know if you need anything else):
#Entity
#Table(name = "EXAMPLE_REQUEST")
#SequenceGenerator(name = "EXAMPLE_REQUEST_ID_SEQ", sequenceName = "EXAMPLE_REQUEST_ID_SEQ", allocationSize = 1)
#Cacheable(false)
public class ExampleRequest implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "EXAMPLE_REQUEST_ID_SEQ")
#Column(name="EXAMPLE_REQUEST_ID", nullable = false)
private Long exampleRequestId;
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "exampleRequest")
private List<ExampleRequestYear> exampleRequestYearList;
public ExampleRequest() {
}
public List<ExampleRequestYear> getExampleRequestYearList() {
if(this.exampleRequestYearList == null){
this.exampleRequestYearList = new ArrayList<ExampleRequestYear>();
}
return this.exampleRequestYearList;
}
public void setExampleRequestYearList(List<ExampleRequestYear> exampleRequestYearList) {
this.exampleRequestYearList = exampleRequestYearList;
}
public ExampleRequestYear addExampleRequestYear(ExampleRequestYear exampleRequestYear) {
getExampleRequestYearList().add(exampleRequestYear);
exampleRequestYear.setExampleRequest(this);
return exampleRequestYear;
}
public ExampleRequestYear removeExampleRequestYear(ExampleRequestYear exampleRequestYear) {
getExampleRequestYearList().remove(exampleRequestYear);
exampleRequestYear.setExampleRequest(null);
return exampleRequestYear;
}
}
#Entity
#Table(name = "EXAMPLE_REQUEST_YEAR")
#IdClass(ExampleRequestYearPK.class)
public class ExampleRequestYear implements Serializable {
#Id
#Column(nullable = false)
private Integer year;
#Id
#ManyToOne
#JoinColumn(name = "EXAMPLE_REQUEST_ID", referencedColumnName = "EXAMPLE_REQUEST_ID")
private ExampleRequest exampleRequest;
public ExampleRequestYear() {
}
public void setExampleRequest(ExampleRequest exampleRequest) {
this.exampleRequest = exampleRequest;
}
public ExampleRequest getExampleRequest() {
return exampleRequest;
}
}
Part of the code was auto-generated by the IDE and I'm still wrapping my head around JPA so there're probably design mistakes all around.
My app works (apparently) when I create a new ExampleRequest:
ExampleRequest exampleRequest = new ExampleRequest();
ExampleRequestYear exampleRequestYear = new ExampleRequestYear(2020);
request.addExampleRequestYear(exampleRequestYear);
However, I can't figure out how to edit an existing ExampleRequest because I'm unsure on how I'm meant to retrieve the linked entities. According to articles I've read, lazy fetching should be automatic, yet when I try this:
ExampleRequest exampleRequest = employeeRequestsController.getExampleRequestById(123);
System.out.println(exampleRequest.getExampleRequestYearList().size());
... I get a null pointer exception upon .size() because the getter runs but neither initialises an empty list, nor retrieves items from DB:
public List<ExampleRequestYear> getExampleRequestYearList() {
if(this.exampleRequestYearList == null){
// Field is null and conditional is entered
this.exampleRequestYearList = new ArrayList<ExampleRequestYear>();
// After initialisation, field is still null!
}
return this.exampleRequestYearList;
}
Also, switch to FetchType.EAGER solves this particular problem entirely. What am I missing?
Further details regarding app design. The Resource classes that handle HTTP requests interact with a set of Controller classes like this:
#Stateless(name = "ISomeActionController", mappedName = "ISomeActionController")
public class SomeActionController implements ISomeActionController {
#EJB
private IFooDAO fooDao;
#EJB
private IBarDAO barDao;
#Override
public ExampleRequest getExampleRequestById(Long exampleRequestId) {
return fooDao.getEntityById(exampleRequestId);
}
}
It's in the DAO classes where EntityManager is injected an used:
#Local
public interface IGenericDAO<T> {
public T persistEntity(T o);
public T persistEntityCommit(T o);
public void removeEntity(T o);
public void removeEntity(long id);
public T mergeEntity(T o);
public List<T> getEntitiesFindAll();
public List<T> getEntitiesFindAllActive();
public T getEntityById(Object id);
}
public interface IFooDAO extends IGenericDAO<ExampleRequest> {
public void flushDAO();
public ExampleRequest getExampleRequestById(Long exampleRequestId);
}
#Stateless(name = "IFooDAO", mappedName = "IFooDAO")
public class FooDAO extends GenericDAO<ExampleRequest> implements IFooDAO {
public FooDAO() {
super(ExampleRequest.class);
}
#Override
public void flushDAO(){
em.flush();
}
#Override
public ExampleRequest getExampleRequestById(Long exampleRequestId){
String sql = "...";
Query query = em.createNativeQuery(sql, ExampleRequest.class);
//...
}
}

ObjectBox: Get objects with specific relations

Expect the two entities Movie and Genre:
#Entity
public class Movie {
#Id
private long id;
private String name;
private ToMany<Genre> genres;
[...]
}
#Entity
public class Genre {
#Id
private long id;
private String name;
[...]
}
We all know how to create a relation and save it:
Movie movie = new Movie();
movie.setTitle("Star Wars");
movie.getGenres().add(new Genre("Sci-Fi");
box.put(movie);
but is there a possibility to query all Movie-objects with a specific Genre? Like
Box<Movie> box = boxStore.boxFor(Movie.class);
Query query = box.query()
.equal(Genre_.name, "Sci-Fi") // note that I want to query the Movie-Box with Genre-properties
.build();
List movies = query.find();
My goal is to find all movies with a specific genre in a simple way. Does anyone know how to do it or do I have to query all movies and filter the result on my own? Or do I have to adapt my entities in another way?
Update:
I prepared the correct marked answer below to a working example:
final Genre genreSciFi = genreBox.query().equal(Genre_.name, "Sci-Fi").build().findFirst();
List<Movie> filteredMovies = movieBox.query().filter(new QueryFilter<Movie>() {
#Override
public boolean keep(#NonNull Movie entity) {
return entity.getGenres().contains(genreSciFi);
}
}).build().find();
To make the contains-Method work correctly, override equals-Method in your Genre-Entity:
#Override
public boolean equals(Object obj) {
return obj instanceof Genre && ((Genre) obj).getId() == id && ((Genre) obj).getName().equals(name);
}

Unfortunately, this part of the API is not exposed in Java yet. We want to refactor the Query API very soon.
Until this is ready, you can workaround using query filtering. Example using Java/Kotlin-ish code for brevity:
Query query = movieBox.query().filter(movie -> {
return genres.contains(genre -> {
return "Sci-Fi".equals(genre.getName())
}
}).build()
(Will make it similar in Java with the next update.)

Hibernate call DELETE from table after method end

I have problem, and I don't know how to solve it.
I have entity:
#Entity
#Table(name = "entity_languagetree")
#AttributeOverride(name = "id", column = #Column(name = "languagetree_id"))
public class LanguageTree extends BaseObject {
#ElementCollection(targetClass = java.lang.String.class, fetch = FetchType.EAGER)
#CollectionTable(name = "view_languagetree_to_stringlist")
private List<String> relationship = new ArrayList<>();
public LanguageTree() {
//
}
public List<String> getRelationship() {
return relationship;
}
public void setRelationship(List<String> relationship) {
this.relationship = relationship;
}
}
where BaseObject is
#MappedSuperclass
public class BaseObject {
#Id
#GeneratedValue
#Column(name = "entity_id")
private Long id;
/**
*
* #return true if the entity hasn't been persisted yet
*/
#Transient
public boolean isNew() {
return id == null;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public Bean getBean() {
return null;
}
}
Work with object - in my servlet, I am calling jsVarTree() like this:
String var = jsVarTree();
My problem is, that after method jsVarTree is finished, hibernate delete my relationship list from entity LanguageTree. I don't know why! I am not calling any delete and etc.. (I AM SURE, I SPENT A LOT OF TIME IN DEBUGER!)
:
#Override
public String jsVarTree() {
TreeBuilder tb = new TreeBuilder(getLanguageList());
return tb.getJsVarString(); // THIS METHOD IS ONLY GETTER !!!!
}
#Override
public List<String> getLanguageList() {
LanguageTree lt = getLanguageTreeObject();
return lt.getRelationship();
}
#Override
public LanguageTree getLanguageTreeObject() {
long fakingId = languageTreeDao.getLastId();
ServerLogger.logDebug("LAST FAKING ID: " +fakingId);
return languageTreeDao.findOne(fakingId);
}
I found this log in loggor:
HibernateLog --> 15:01:03 DEBUG org.hibernate.SQL - delete from
view_languagetree_to_stringlist where LanguageTree_languagetree_id=?
Can somebody tell me, why hibernate call delete over my table?
I saw a table in phpmyadmin..
TABLE IS FULL.
String var = jsVarTree();
TABLE IS EMPTY.
Table is deleted after return tb.getJsVarString(); is finished.
Thank you for any help!

Recurrsive loop on method call, unsure if it is related to mapping

I'm having some issues with my entity mapping on these objects. I don't get an exception but it seems like it goes into a recursive loop
public class LabResult implements java.io.Serializable {
private Long labResultId;
private Customer customer;
private LabResultUnprocessed labResultUnprocessed;
public LabResult(){
}
public LabResult(Long labResultId) {
this.labResultId = labResultId;
}
public LabResult(Long labResultId, Customer customer, LabResultUnprocessed labResultUnprocessed) {
this.labResultId = labResultId;
this.customer = customer;
this.labResultUnprocessed = labResultUnprocessed;
}
#OneToOne(fetch=FetchType.LAZY, mappedBy="labResult")
#JoinColumn(name="lab_result_id")
public LabResultUnprocessed getLabResultUnprocessed(){
return labResultUnprocessed;
}
public void setLabResultUnprocessed(LabResultUnprocessed labResultUnprocessed) {
this.labResultUnprocessed = labResultUnprocessed;
}
The next domain is LabResultUnprocessed
#Entity
#Table(name="lab_result_unprocessed"
,schema="public"
)
public class LabResultUnprocessed implements java.io.Serializable {
private LabResult labResult;
private Boolean processedFlag;
public LabResultUnprocessed() {
}
public LabResultUnprocessed(LabResult labResult, Boolean processedFlag) {
this.labResult = labResult;
this.processedFlag = processedFlag;
}
#Id
#OneToOne(fetch=FetchType.LAZY)
#JoinColumn(name="lab_result_id")
public LabResult getLabResult() {
return labResult;
}
public void setLabResult(LabResult labResult) {
this.labResult = labResult;
}
Here is the LabResultUnprocessedRepository
public interface LabResultUnprocessedRepository extends CrudRepository<LabResult, String>{
#Query("select lru from LabResultUnprocessed lru "
+" join fetch lru.labResult lr "
+" where lru.labResult.labResultId = lr.labResultId "
+" and lru.processedFlag = false")
List<LabResultUnprocessed> findAllByProcessedFlag();
In my service when I call this method it seems like it goes into a recursive loop and never hits my breakpoint which is on the actual method call in this 2nd line.
List<LabResultUnprocessed> allUnprocessedResults = new ArrayList<LabResultUnprocessed>();
allUnprocessedResults = labResultUnprocessedRepository.findAllByProcessedFlag();
allUnprocessedResults.forEach(lru -> {
...////

You have two problems in this section:
#OneToOne(fetch=FetchType.LAZY, mappedBy="testResult")
#JoinColumn(name="test_result_id")
mappedBy and #JoinColumn don't go together. One end of the relationship should have one, and the other end should have the other. Neither end should have both. Remove #JoinColumn from this end to fix this.
The value of mappedBy needs to be the name of the field on the other end of the relationship - in this case, labResult.

Can't remove entity with JPA

I'm trying to remove an entity from memory (at the moment I don't use DB) with JPA, when I use remove and then try to find the deleted entity it shows null, but when I use findAll method it retrieve all data (with removed entity)...
Profile.java
#Entity
#Table(name = "profile")
public class Profile {
#Id
#GeneratedValue
private Long id;
private String nombre;
private Boolean restrictedAccess;
private Boolean canValidate;
// private Set<AccessField> accessFields = new HashSet<AccessField>();
// private Set<AccessEntity> accessEntities = new HashSet<AccessEntity>();
#OneToMany(mappedBy = "profile", fetch = FetchType.EAGER)
private Set<AccessMenu> menuSections = new HashSet<AccessMenu>();
#OneToMany(mappedBy = "profile", fetch = FetchType.EAGER)
private Set<User> users = new HashSet<User>();
[getters and setters]
ProfileRepository
#Repository
#Transactional
public class ProfileRepository {
#PersistenceContext
private EntityManager entityManager;
public Profile save(Profile p) {
p = this.entityManager.merge(p);
this.entityManager.flush();
return p;
}
public void delete(Long id){
Profile profile = this.entityManager.find(Profile.class, id);
this.entityManager.remove(profile);
}
public List<Profile> findAll() {
CriteriaQuery cq = this.entityManager.getCriteriaBuilder().createQuery();
cq.select(cq.from(Profile.class));
return (List<Profile>) this.entityManager.createQuery(cq).getResultList();
}
public Profile findById(Long id){
return this.entityManager.find(Profile.class, id);
}
}
Controller method
#RequestMapping(value="profile/delete/{idProfile}", method = RequestMethod.GET)
public String delete(#PathVariable String idProfile,RedirectAttributes ra, Model model){
profileRepo.delete(Long.valueOf(idProfile));
model.addAttribute("profiles", profileRepo.findAll());
return "profile/list";
}

if you are are trying to delete an entity by using Id in the controller, do it like profileRepo.deleteById(Long.valueOf(idProfile));
this, not like this profileRepo.delete(profileRepo.findById(Long.valueOf(idProfile)));
Also use your repository functions like these,
public void deleteArtistById(Long artistId) {
Artist artist = manager.find(Artist.class, artistId);
if (artist != null) {
manager.getTransaction().begin();
manager.remove(artist);
manager.getTransaction().commit();
}
}
public void deleteArtist(Artist artist) {
manager.getTransaction().begin();
manager.remove(artist);
manager.getTransaction().commit();
}
You can take a look at this link for more detail:
http://kodejava.org/how-do-i-delete-entity-object-in-jpa/

At last I found a solution, the problem was when I tried to remove Profile, users and menuSections have related data, so finally I put in menuSections a cascade = CascadeType.REMOVE and in users set profile property to null