Question

I have two tables between which I am trying to establish a 1-to-1 mapping using Hibernate.

ExamDetail.java

package com.hibernate.mapping;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="exam_detail")
public class ExamDetail {

    private int id;
    private String fullName;
    private int numberOfQuestions;
    private int passingPercentage;

    @Id
    @GeneratedValue
    @Column(name="id")
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getFullName() {
        return fullName;
    }
    public void setFullName(String fullName) {
        this.fullName = fullName;
    }
    public int getNumberOfQuestions() {
        return numberOfQuestions;
    }
    public void setNumberOfQuestions(int numberOfQuestions) {
        this.numberOfQuestions = numberOfQuestions;
    }
    public int getPassingPercentage() {
        return passingPercentage;
    }
    public void setPassingPercentage(int passingPercentage) {
        this.passingPercentage = passingPercentage;
    }
}

Exam.java

package com.hibernate.mapping;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name="exam")
public class Exam {

    private int id;
    private String shortName;
    private ExamDetail detail;

    @Id
    @GeneratedValue
    @Column(name="id")
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getShortName() {
        return shortName;
    }
    public void setShortName(String shortName) {
        this.shortName = shortName;
    }

    @OneToOne(cascade=CascadeType.PERSIST)
    @JoinColumn(name="detail_id")
    public ExamDetail getDetail() {
        return detail;
    }
    public void setDetail(ExamDetail detail) {
        this.detail = detail;
    }
}

TestMapping.java

package com.hibernate.mapping;

import org.hibernate.Session;

import com.hibernate.util.HibernateUtil;

public class TestMapping {

    public static void main(String[] args) {
        Session session = HibernateUtil.beginTransaction();

        Exam exam = new Exam();
        exam.setShortName("SCJA");

        ExamDetail detail = new ExamDetail();
        detail.setFullName("Sun Certified Associate");
        detail.setNumberOfQuestions(50);
        detail.setPassingPercentage(60);

        exam.setDetail(detail);

        session.save(exam);
        HibernateUtil.commitTransaction();
    }
}

When I ran this code, I encounter following exception :-

Exception in thread “main”
org.hibernate.exception.ConstraintViolationException: could not
insert: [com.hibernate.mapping.Exam] at
org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:94)
at
org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at
org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:64)
at
org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2186)
at
org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2666)
at
org.hibernate.action.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:71)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:279) at
org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:321)
at
org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:204)
at
org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:130)
at
org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
at
org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:56)
at
org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
at
org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:50)
at
org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:562) at
org.hibernate.impl.SessionImpl.save(SessionImpl.java:550) at
org.hibernate.impl.SessionImpl.save(SessionImpl.java:546) at
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at
java.lang.reflect.Method.invoke(Unknown Source) at
org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:342)
at $Proxy14.save(Unknown Source) at
com.hibernate.mapping.TestMapping.main(TestMapping.java:22) Caused by:
com.sybase.jdbc2.jdbc.SybSQLException: The column detail_id in table
exam does not allow null values.

at com.sybase.jdbc2.tds.Tds.processEed(Tds.java:2535) at
com.sybase.jdbc2.tds.Tds.nextResult(Tds.java:1916) at
com.sybase.jdbc2.jdbc.ResultGetter.nextResult(ResultGetter.java:69)
at
com.sybase.jdbc2.jdbc.SybStatement.nextResult(SybStatement.java:201)
at
com.sybase.jdbc2.jdbc.SybStatement.nextResult(SybStatement.java:182)
at
com.sybase.jdbc2.jdbc.SybStatement.executeLoop(SybStatement.java:1596)
at com.sybase.jdbc2.jdbc.SybStatement.execute(SybStatement.java:1588)
at
com.sybase.jdbc2.jdbc.SybPreparedStatement.execute(SybPreparedStatement.java:580)
at
org.hibernate.id.IdentityGenerator$InsertSelectDelegate.executeAndExtract(IdentityGenerator.java:138)
at
org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:57)
… 22 more

What am I doing wrong ?

Any missing statement ?

Answer 1

You need to reference ID generation in JPA.

Here : reference

JPA Example

ID Generation