'JPA/Hibernate @GenericGenerator throws StackOverFlow on persisting entity
I have implemented two entities (Department and Employee) with custom ID generator for Employee, and has a unidirectional one-to-many relationship as shown below:-
Department Class
@Setter
@Getter
@NoArgsConstructor
@Entity(name = "department")
@Table(name = "department")
public class Department {
@Id
@Column(columnDefinition = "char(36)")
@GeneratedValue(generator = "dept-generator")
@GenericGenerator(name = "dept-generator", strategy = "org.hibernate.id.UUIDGenerator")
private String id;
@Basic
@Column(length = 50, nullable = false)
private String name;
@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
@JoinTable(
name = "dept_emp",
joinColumns = @JoinColumn(name = "dept_id", referencedColumnName = "id", nullable = false),
inverseJoinColumns = @JoinColumn(name = "emp_id", referencedColumnName = "id", nullable = false),
foreignKey = @ForeignKey(ConstraintMode.CONSTRAINT),
inverseForeignKey = @ForeignKey(ConstraintMode.CONSTRAINT)
)
private Set<Employee> employees;
public Department(String name, Set<Employee> employees) {
this.name = name;
this.employees = employees;
}
}
Employee Class
@Setter
@Getter
@NoArgsConstructor
@Entity(name = "employee")
@Table(name = "employee")
public class Employee {
@Id
@Column(columnDefinition = "char(13)")
@GeneratedValue(generator = "emp-generator")
@GenericGenerator(name = "emp-generator", strategy = "com.query.example.EmployeeIdGenerator")
private String id;
@Basic
@Column(length = 50, nullable = false)
private String name;
@Basic
@Column(nullable = false)
private double salary;
@Basic
@Column(length = 50, nullable = false)
private String qualification;
public Employee(String name, double salary, String qualification) {
this.name = name;
this.salary = salary;
this.qualification = qualification;
}
}
EmployeeIdGenerator Class
public class EmployeeIdGenerator implements IdentifierGenerator {
private static final DateTimeFormatter DATE_FORMATTER = DateTimeFormatter.ofPattern("yyyyMM");
private static final String FORMAT = "E%s%05d";
@Override
public Serializable generate(SharedSessionContractImplementor session, Object obj) throws HibernateException {
SessionImpl session1 = (SessionImpl) session;
CriteriaBuilder builder = session1.getCriteriaBuilder();
EmployeeSequence sequence = new EmployeeSequence();
try {
CriteriaQuery<EmployeeSequence> criteria = builder.createQuery(EmployeeSequence.class);
Root<EmployeeSequence> root = criteria.from(EmployeeSequence.class);
criteria.select(root).where(
builder.equal(root.get("id"), 1),
builder.equal(root.get("date"), sequence.getDate())
);
sequence = session1.createQuery(criteria).getSingleResult();
} catch (Exception ex) {
try {
CriteriaQuery<EmployeeSequence> criteria = builder.createQuery(EmployeeSequence.class);
Root<EmployeeSequence> root = criteria.from(EmployeeSequence.class);
criteria.select(root).where(builder.equal(root.get("id"), 1));
sequence = session1.createQuery(criteria).getSingleResult();
sequence.init();
} catch (Exception ex1) {
}
}
int counter = sequence.increment();
session1.merge(sequence);
return String.format(FORMAT, sequence.getDate().format(DATE_FORMATTER), counter);
}
}
EmployeeSequence Class
@Setter
@Getter
@NoArgsConstructor
@Entity(name = "employee_sequence")
@Table(name = "employee_sequence")
public class EmployeeSequence {
@Id
private int id = 1;
@Basic
private LocalDate date = YearMonth.now().atDay(1);
@Basic
@Column(length = 5, nullable = false, unique = true)
private int counter = 1;
public void init() {
this.date = YearMonth.now().atDay(1);
this.counter = 1;
}
/**
* This method will return the pre increment value of counter
*/
public int increment() {
return counter++;
}
@Override
public int hashCode() {
return UUID.randomUUID().hashCode();
}
}
And here is an example for persisting a Department has a set of employees:-
Set<Employee> employees = new HashSet<>(Arrays.asList(
new Employee("EMP1", 123, "PhD"),
new Employee("EMP2", 321, "MA"),
new Employee("EMP3", 101, "PhD")
));
Department csDept = new Department("Computer Science", employees);
entityManager.getTransaction().begin();
entityManager.persist(csDept);
entityManager.getTransaction().commit();
After running the above example i got StackOverFlow error on EmployeeIdGenerator.generate(EmployeeIdGenerator.java:34) as shown below:-
Exception in thread "main" java.lang.StackOverflowError
at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:675)
at java.lang.StringBuilder.append(StringBuilder.java:208)
at org.hibernate.query.criteria.internal.compile.CriteriaCompiler$1.generateParameterName(CriteriaCompiler.java:77)
at org.hibernate.query.criteria.internal.compile.CriteriaCompiler$1.registerLiteralParameterBinding(CriteriaCompiler.java:124)
at org.hibernate.query.criteria.internal.expression.LiteralExpression.bindLiteral(LiteralExpression.java:131)
at org.hibernate.query.criteria.internal.expression.LiteralExpression.normalRender(LiteralExpression.java:87)
at org.hibernate.query.criteria.internal.expression.LiteralExpression.render(LiteralExpression.java:74)
at org.hibernate.query.criteria.internal.predicate.ComparisonPredicate.render(ComparisonPredicate.java:172)
at org.hibernate.query.criteria.internal.predicate.AbstractSimplePredicate.render(AbstractSimplePredicate.java:48)
at org.hibernate.query.criteria.internal.predicate.CompoundPredicate.render(CompoundPredicate.java:162)
at org.hibernate.query.criteria.internal.predicate.CompoundPredicate.render(CompoundPredicate.java:115)
at org.hibernate.query.criteria.internal.predicate.CompoundPredicate.render(CompoundPredicate.java:105)
at org.hibernate.query.criteria.internal.QueryStructure.renderWhereClause(QueryStructure.java:372)
at org.hibernate.query.criteria.internal.QueryStructure.render(QueryStructure.java:238)
at org.hibernate.query.criteria.internal.CriteriaQueryImpl.interpret(CriteriaQueryImpl.java:297)
at org.hibernate.query.criteria.internal.compile.CriteriaCompiler.compile(CriteriaCompiler.java:165)
at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:751)
at com.query.example.EmployeeIdGenerator.generate(EmployeeIdGenerator.java:34)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:115)
at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185)
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128)
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:104)
at org.hibernate.internal.SessionImpl.persistOnFlush(SessionImpl.java:765)
at org.hibernate.engine.spi.CascadingActions$8.cascade(CascadingActions.java:341)
at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:492)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:416)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:218)
at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:525)
at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:456)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:419)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:218)
at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:151)
at org.hibernate.event.internal.AbstractFlushingEventListener.cascadeOnFlush(AbstractFlushingEventListener.java:159)
at org.hibernate.event.internal.AbstractFlushingEventListener.prepareEntityFlushes(AbstractFlushingEventListener.java:149)
at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:82)
at org.hibernate.event.internal.DefaultAutoFlushEventListener.onAutoFlush(DefaultAutoFlushEventListener.java:50)
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:93)
at org.hibernate.internal.SessionImpl.autoFlushIfRequired(SessionImpl.java:1327)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1407)
at org.hibernate.query.internal.AbstractProducedQuery.doList(AbstractProducedQuery.java:1625)
at org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1593)
at org.hibernate.query.internal.AbstractProducedQuery.getSingleResult(AbstractProducedQuery.java:1641)
at org.hibernate.query.criteria.internal.compile.CriteriaQueryTypeQueryAdapter.getSingleResult(CriteriaQueryTypeQueryAdapter.java:111)
What is the reason that makes EmployeeIdGenerator throws this error when is use persist()?
Sources
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Source: Stack Overflow
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