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JpaObjectRetrievalFailureException when saving entity with one-to-many and client-assigned ids

In a simple Spring Boot Application, I'm facing with a JpaObjectRetrievalFailureException when I'm trying to save an entity with one-to-many association and client-assigned ids.
Please take a look on these entities and on this simple repository:
#Entity
#Table(name = "cart")
public class Cart {
#Id
#Column(name = "id")
private UUID id;
#Column(name = "name")
private String name;
#OneToMany
#JoinColumn(name = "cart_id")
private List<Item> items;
// constructors, getters, setters, equals and hashCode ommitted
}
#Entity
#Table(name = "item")
public class Item {
#Id
#Column(name = "id")
private UUID id;
#Column(name = "name")
private String name;
// constructors, getters, setters, equals and hashCode ommitted
}
public interface CartRepository extends JpaRepository<Cart, UUID> {
}
I wrote this test:
#DataJpaTest
class CartRepositoryTest {
#Autowired
private CartRepository cartRepository;
#Test
void should_save_cart() {
// GIVEN
final var cart = new Cart(UUID.randomUUID(), "cart");
final var item = new Item(UUID.randomUUID(), "item");
cart.setItems(List.of(item));
// WHEN
final var saved = cartRepository.save(cart);
// THEN
final var fetched = cartRepository.findById(saved.id());
assertThat(fetched).isPresent();
}
}
When I run the test, call to cartRepository.save(cart) fails with:
Unable to find com.example.testjpaonetomany.domain.Item with id f5658508-f3d0-4d9b-a1f0-17b614753356; nested exception is javax.persistence.EntityNotFoundException: Unable to find com.example.testjpaonetomany.domain.Item with id f5658508-f3d0-4d9b-a1f0-17b614753356
org.springframework.orm.jpa.JpaObjectRetrievalFailureException: Unable to find com.example.testjpaonetomany.domain.Item with id f5658508-f3d0-4d9b-a1f0-17b614753356; nested exception is javax.persistence.EntityNotFoundException: Unable to find com.example.testjpaonetomany.domain.Item with id f5658508-f3d0-4d9b-a1f0-17b614753356
at app//org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:379)
at app//org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:235)
at app//org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:551)
at app//org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:61)
at app//org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:242)
at app//org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:152)
at app//org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at app//org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:174)
at app//org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at app//org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97)
at app//org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at app//org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215)
at app/jdk.proxy3/jdk.proxy3.$Proxy105.save(Unknown Source)
at app//com.example.testjpaonetomany.repository.CartRepositoryTest.should_save_cart(CartRepositoryTest.java:28)
If I modify my entities by adding #GeneratedValue for ids, and in my test, I replace UUID.randomUUID() by null to delegate to Hibernate the ID generation, the test passes.
How to deal with client-generated ids?

The cause is that you save the parent object only (which is absolutely correct and fine) but still need to explain JPA that the operation should be propagated i.e.
#OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
#JoinColumn(name = "cart_id")
private List<Item> items;
As minor improvements I would suggest to put the UUID generation into constructors and establish the relation via the dedicated method i.e.
final var cart = new Cart("cart");
cart.addItem(new Item("item"));
and probably consider using em.persist() instead of repository.save() as it makes a select request first in case of using uuids as #Augusto mentioned

How to avoid LazyInitializationException with nested collections in JPA-Hibernate?

Mandatory background info:
As part of my studies to learn Spring, I built my usual app - a little tool that saves questions and later creates randomized quizzes using them.
Each subject can have any number of topics, which in turn may have any number of questions, which once again in turn may have any number of answers.
Now, the problem proper:
I keep getting LazyInitializationExceptions.
What I tried last:
I changed almost each and every collection type used to Sets.
Also felt tempted to set the enable_lazy_load_no_trans property to true, but I've consistently read this is an antipattern to avoid.
The entities proper: (only fields shown to avoid wall of code-induced fatigue)
Subject:
#Entity
#Table(name = Resources.TABLE_SUBJECTS)
public class Subject implements DomainObject
{
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = Resources.ID_SUBJECT)
private int subjectId;
#Column(name="subject_name", nullable = false)
private String name;
#OneToMany(
mappedBy = Resources.ENTITY_SUBJECT,
fetch = FetchType.EAGER
)
private Set<Topic> topics;
}
Topic:
#Entity
#Table(name = Resources.TABLE_TOPICS)
public class Topic implements DomainObject
{
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "topic_id")
private int topicId;
#Column(name = "name")
private String name;
#OneToMany(
mappedBy = Resources.ENTITY_TOPIC,
orphanRemoval = true,
cascade = CascadeType.MERGE,
fetch = FetchType.EAGER
)
private Set<Question> questions;
#ManyToOne(
fetch = FetchType.LAZY
)
private Subject subject;
}
Question:
#Entity
#Table(name = Resources.TABLE_QUESTIONS)
public class Question implements DomainObject
{
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = Resources.ID_QUESTION)
private int questionId;
#Column(name = "statement")
private String statement;
#OneToMany(
mappedBy = Resources.ENTITY_QUESTION,
orphanRemoval = true,
cascade = CascadeType.MERGE
)
private Set<Answer> answers;
#ManyToOne(
fetch = FetchType.LAZY
)
private Topic topic;
}
Answer:
#Entity
#Table(name = Resources.TABLE_ANSWERS)
public class Answer implements DomainObject
{
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = Resources.ID_ANSWER)
private int answerId;
#Column(name = "answer_text", nullable = false)
private String text;
#Column(name = "is_correct", nullable = false)
private Boolean isCorrect;
#ManyToOne(
fetch = FetchType.LAZY
)
private Question question;
}
I'm using interfaces extending JpaRepository to perform CRUD operations. I tried this to fetch stuff, without luck:
public interface SubjectRepository extends JpaRepository<Subject, Integer>
{
#Query
Optional<Subject> findByName(String name);
#Query(value = "SELECT DISTINCT s FROM Subject s " +
"LEFT JOIN FETCH s.topics AS t " +
"JOIN FETCH t.questions AS q " +
"JOIN FETCH q.answers as a")
List<Subject> getSubjects();
}
Now, the big chunk of text Spring Boot deigns to throw at me - the stack trace:
Caused by: org.hibernate.LazyInitializationException: could not initialize proxy [org.callisto.quizmaker.domain.Subject#1] - no Session
at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:176) ~[hibernate-core-5.6.4.Final.jar:5.6.4.Final]
at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:322) ~[hibernate-core-5.6.4.Final.jar:5.6.4.Final]
at org.hibernate.proxy.pojo.bytebuddy.ByteBuddyInterceptor.intercept(ByteBuddyInterceptor.java:45) ~[hibernate-core-5.6.4.Final.jar:5.6.4.Final]
at org.hibernate.proxy.ProxyConfiguration$InterceptorDispatcher.intercept(ProxyConfiguration.java:95) ~[hibernate-core-5.6.4.Final.jar:5.6.4.Final]
at org.callisto.quizmaker.domain.Subject$HibernateProxy$B8rwBfBD.getTopics(Unknown Source) ~[main/:na]
at org.callisto.quizmaker.service.QuizMakerService.activeSubjectHasTopics(QuizMakerService.java:122) ~[main/:na]
at org.callisto.quizmaker.QuizMaker.checkIfActiveSubjectHasTopics(QuizMaker.java:307) ~[main/:na]
at org.callisto.quizmaker.QuizMaker.createNewQuestion(QuizMaker.java:117) ~[main/:na]
at org.callisto.quizmaker.QuizMaker.prepareMainMenu(QuizMaker.java:88) ~[main/:na]
at org.callisto.quizmaker.QuizMaker.run(QuizMaker.java:65) ~[main/:na]
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:769) ~[spring-boot-2.6.3.jar:2.6.3]
This exception happens when I call this line of code:
boolean output = service.activeSubjectHasTopics();
Which, in turn, calls this method on a service class:
public boolean activeSubjectHasTopics()
{
if (activeSubject == null)
{
throw new NullPointerException(Resources.EXCEPTION_SUBJECT_NULL);
}
return !activeSubject.getTopics().isEmpty();
}
The activeSubjectHasTopics method gets called in this context:
private void createNewQuestion(View view, QuizMakerService service)
{
int subjectId = chooseOrAddSubject(view, service);
service.setActiveSubject(subjectId);
if (checkIfActiveSubjectHasTopics(view, service))
{
chooseOrAddTopic(view, service, subjectId);
}
do
{
createQuestion(view, service);
createAnswers(view, service);
}
while(view.askToCreateAnotherQuestion());
service.saveDataToFile();
prepareMainMenu(view, service);
}
private boolean checkIfActiveSubjectHasTopics(View view, QuizMakerService service)
{
boolean output = service.activeSubjectHasTopics();
if (!output)
{
view.printNoTopicsWarning(service.getActiveSubjectName());
String topicName = readTopicName(view);
createNewTopic(service, topicName);
}
return output;
}

Not helpful if you change your structure to set. If you need to get the entities you need to explicitly include FETCH clause in your hql queries. You'll work your way by checking out the Hibernate documentation:
https://docs.jboss.org/hibernate/orm/3.3/reference/en/html/performance.html#performance-fetching

I was able to track down the cause of the issue thanks to a comment from Christian Beikov - to quote:
Where do you get this activeSubject object from? If you don't load it
as part of the transaction within activeSubjectHasTopics, then this
won't work as the object is already detached at this point, since it
was loaded through a different transaction.
The activeSubject object was defined as part of the service class containing the activeSubjectHasTopics method, and was initialized by a different transaction as he pointed out.
I was able to fix the problem by annotating that service class as #Transactional and storing the IDs of the objects I need instead of the objects themselves.

How to use graphql with jpa if schema is different to database structure

There is a given database structure and graphql schema.
Fortunately they have a lot in common but unfortunately there are some difference.
Let's say there are entities in java to match the following database structure.
SQL:
TABLE ANIMAL
+ID NUMBER(19)
+NR_OF_LEGS NUMBER(19)
TABLE SHEEP
+ID NUMBER
+LAST_TIME_SHEARED DATETIME
+ANIMAL_ID NUMBER(19)
TABLE COW
+MILK_IN_L NUMBER(3)
+ANIMAL_ID NUMER(19)
Java:
#Entity
#Table(name = "ANIMAL")
public class Animal
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
#Column(name="nrOfLegs", nullable=false)
private long nrOfLegs;
}
#Entity
#Table(name = "SHEEP")
public class SheepE
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
#Column(name="lastTimeSheared", nullable=false)
private Datetime lastTimeSheared;
#ManyToOne(targetEntity = AnimalE.class, cascade = CascadeType.ALL, fetch = FetchType.LAZY, optional = true)
#JoinColumn(name = "animalId", nullable = false, insertable = false, updatable = false)
private Animal animal;
}
#Entity
#Table(name = "COW")
public class CowE
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
#Column(name="milkInL", nullable=false)
private int milkInL;
#ManyToOne(targetEntity = AnimalE.class, cascade = CascadeType.ALL, fetch = FetchType.LAZY, optional = true)
#JoinColumn(name = "animalId", nullable = false, insertable = false, updatable = false)
private Animal animal;
}
The existing GraphQl schema is considered to be like this:
type Sheep{
id: int!
lastTimeSheard: String!
nrOfLegs: int!
}
type Cow {
id: int!
milkInL: int!
nrOfLegs: int
}
The project uses graphql-java in version 11.0 (guess we should update soon)
<dependency>
<groupId>com.graphql-java</groupId>
<artifactId>graphql-java</artifactId>
<version>11.0</version>
</dependency>
The graphql works fine and isimplemented like this:
#Component
public class GraphQLProvider {
#Autowired
GraphQLDataFetchers graphQLDataFetchers;
private GraphQL graphQL;
#PostConstruct
public void init() {this.graphQL = /*init;*/null;}
private RuntimeWiring buildWiring() {
RuntimeWiring.Builder b = RuntimeWiring.newRuntimeWiring()
.type(TypeRuntimeWiring.newTypeWiring("Query")
.dataFetcher("freightCarrier", graphQLDataFetchers.getCow()))
.type(TypeRuntimeWiring.newTypeWiring("Query")
.dataFetcher("personCarrier", graphQLDataFetchers.getSheep())));
return b.build();
}
}
#Component
public class GraphQLDataFetchers {
#AutoWired
private CowRepository cowRepo;
#AutoWired
private sheepRepository sheepRepo;
public DataFetcher getCow() {
DataFetcher dataFetcher = (DataFetchingEnvironment dfe) -> {
int id = dfe.getArgument("id");
return getGraphQlCowFromCowEntity(cowRepo.getById(id));//dirty!
};
return dataFetcher;
}
public DataFetcher getCow() {
DataFetcher dataFetcher = (DataFetchingEnvironment dfe) -> {
int id = dfe.getArgument("id");
return getGraphQlSheepFromSheepEntity(cowRepo.getById(id));//dirty!
};
return dataFetcher;
}
private Cow getGraphQlCowFromCowEntity(CowE ce){//dirty!
return new Cow(ce.getId(), ce.getMilkInL(),ce.getLegs());
}
private Sheep getGraphQlSheepFromSheepEntity(SheepE se){//dirty!
return new Sheep(se.getId(), se.getLastTime(),se.getLegs());
}
public class Sheep
private long id;
private Datetime lastTimeSheared;
private int nrOfLegs;
public Sheep(long id, DateTime lasttimeSheared, int nrOfLegs){
//u know what happens here
}
}
public class Cow
private long id;
private int milkInL;
private int nrOfLegs;
public Sheep(long id, int milkInL, int nrOfLegs){
//u know what happens here
}
}
So how to get rid of getGraphQlCowFromCowEntity and getGraphQlSheepFromSheepEntity. It double ups the code and also is in direct conflict to what graphql is suppose to be abstraction of the data. With this design here each time all fields are loaded through jpa and not only requested fields.
Imagine this is a way more complex environment with more fields.
The graphql schema can't be changed as it's not my responsibility, changing the entire back-end to match schema is also not what I want to archive.
Kind regards

You should use DTO. Retrieving and sending entity object is bad practice as you do not want your grahql api to change every time you refactor you database model, or in your case. Your Sheep and Cow objects are DTO, but you will need some way to convert your entity to DTO (getGraphQlCowFromCowEntity is fine, but you could use polymorphism - CowEntity.toDTO() - or have a service layer do the conversion, there are plenty of way to do this).
To answer your concerns about loading only the requested data, you want your DTO object to only be populated with the requested fields. One way to do this is, instead of populating all fields, have the DTO own a reference to the entity object and retrieve the data from the entity object only when requested.
public class Sheep {
private SheepE entity;
public Sheep(SheepE entity){
this.entity=entity;
}
public getId() {
return entity.getId();
}
public getLastTimeSheared() {
return entity.getLastTimeSheared();
}
...
}
Please see this answer I wrote to a similar question: Graphql Tools: Map entity type to graphql type

#Formula not working in hibernate with object

I have a enum of few status value
NEW, REVIEWD, PUBLISHED, PENDING, UPDATED, SPAM, DUPLICATE, IRRELEVANT, UNPUBLISHED
I don't want to use them as enumerated so created one entity for that. For convenient I want to keep a column in entity to initialize status from enum and convert that enumerated value to a Object of status entity. for this..
I have two entity. I want to refer a column with value from another entity.
Basically I want to initialize a object with formula.
Entities are
#Entity
#Table(name = "event_status")
public class EventStatus {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name="eventStatusId")
private Integer eventStatusId;
#Enumerated(EnumType.STRING)
#Column(unique = true,name="eventStatusType")
private EventStatusType eventStatusType;
public EventStatus() {
this(EventStatusType.NEW);
}
public EventStatus(EventStatusType eventStatusType) {
super();
this.eventStatusType = eventStatusType;
}
public Integer getEventStatusId() {
return eventStatusId;
}
public EventStatusType getEventStatusType() {
return eventStatusType;
}
public void setEventStatusId(Integer eventStatusId) {
this.eventStatusId = eventStatusId;
}
public void setEventStatusType(EventStatusType eventStatusType) {
this.eventStatusType = eventStatusType;
}
}
I have another entity in which I am referring object of this entity
#Entity
#Table(name = "event_")
#Inheritance(strategy = InheritanceType.JOINED)
public abstract class Event implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Column(name = "id_")
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#Transient
public EventStatusType eventStatusType = EventStatusType.NEW;
#ManyToOne(fetch = FetchType.EAGER, targetEntity = EventStatus.class)
#Formula("select * from event_status where eventStatusId= 1")
private EventStatus status;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public EventStatus getStatus() {
System.out.println("Event.getStatus() " + status);
return status;
}
public void setStatus(EventStatus status) {
System.out.println("Event.setStatus()");
this.status = status;
}
}
This is not giving any exception but not initializing this value.
Is it possible to initialize this EntityStatus with value of eventStatusType in Event entity

I would like to explain that based on the documentation:
5.1.4.1.5. Formula
Sometimes, you want the Database to do some computation for you rather than in the JVM, you might also create some kind of virtual column. You can use a SQL fragment (aka formula) instead of mapping a property into a column. This kind of property is read only (its value is calculated by your formula fragment).
#Formula("obj_length * obj_height * obj_width")
public long getObjectVolume()
The SQL fragment can be as complex as you want and even include subselects.
...
5.1.7.1. Using a foreign key or an association table
...
Note
You can use a SQL fragment to simulate a physical join column using the #JoinColumnOrFormula / #JoinColumnOrformulas annotations (just like you can use a SQL fragment to simulate a property column via the #Formula annotation).
#Entity
public class Ticket implements Serializable {
#ManyToOne
#JoinColumnOrFormula(formula="(firstname + ' ' + lastname)")
public Person getOwner() {
return person;
}
...
}
Also, we should use insertable = false, updatable = false, because such mapping is not editable

JPA/Hibernate Persist cascades even if it shouldn't

I got these 2 entities:
#javax.persistence.Entity
public class Book {
#javax.persistence.EmbeddedId
private BookPK id;
private String title;
#javax.persistence.ManyToOne(fetch = javax.persistence.FetchType.LAZY)
#javax.persistence.JoinColumns({
#javax.persistence.JoinColumn(name = "LNGCOD", referencedColumnName = "LNGCOD"),
#javax.persistence.JoinColumn(name = "LIBCOD", referencedColumnName = "LIBCOD") })
private Language language;
}
#javax.persistence.Entity
public class Language {
#javax.persistence.EmbeddedId
private LanguagePK id;
private String name;
}
with composed PK's:
#Embeddable
public class BookPK implements Serializable {
private Integer bookcod;
private Integer libcod;
}
#Embeddable
public class LanguagePK implements Serializable {
private Integer lngcod;
private Integer libcod;
}
If I try to create a new Book and persist it, I get an exception telling me libcod is found twice in the insert statement ("Column 'libcod' specified twice"). But I can't use "insertable = false" when defining the JoinColumn ("Mixing insertable and non insertable columns in a property is not allowed").
Is there any way to define these objects + relationship so the columns are managed automatically by Hibernate ?

Hibernate and JPA automatically make persistent all the modifications made to persistent entities while they are attached to the session. That's the whole point of an ORM: you load a persistent object, modify it, and the new state is automatically persisted at the commit of the transaction, without any need to call persist, merge, save or any other method.
Note that calling persist on a persistent entities (except for its cascading side-effects) makes no sense. persist is to make a transient entity (i.e. a new one, not in the database yet, with no generated ID) persistent.

You can only have one mutator for the libcod. Probably, what you should do is leave the libcod getter in the BookPK class, and in the Language class, use a joincolumn reference with a ref back to the libcod. It works fine for single embedded PK classes, but for multiple PK classes, you may have to play around.
So, in your Language class, you would have this.
#javax.persistence.Entity public class Language {
private LanguagePK id;
private Integer libcod;
#javax.persistence.EmbeddedId #AttributeOverrides({
#AttributeOverride(name = "lngcod", column = #Column(name = "LNGCOD", nullable = false)),
#AttributeOverride(name = "libcod", column = #Column(name = "LIBCOD", nullable = false)) })
public LanguagePK getId() {
return this.id;
}
public void setId(LanguagePK id) {
this.id = id;
}
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "LIBCOD", insertable = false , updatable = false)
public Integer getLibcod() {
return this.libcod;
}