Hi all,

On my way in understanding the transaction-type attribute of persistence.xml, i came across an issue / discrepency between hibernate-core and JPA-hibernate which looks weird.

I am not pretty sure whether it is a missing implementation with JPA of hibernate.

Let me post the comparison between the outcome of JPA implementation and the hibernate implementation of the same concept.

Environment

1. Eclipse 3.5.1
2. JSE v1.6.0_05
3. Hibernate v3.2.3 [for hibernate core]
4. Hibernate-EntityManger v3.4.0 [for JPA]
5. MySQL DB v5.0

Issue

1.Hibernate core

package com.expt.hibernate.core;

import java.io.Serializable;

public final class Student implements Serializable {

    private int studId;

    private String studName;

    private String studEmailId;

    public Student(final String studName, final String studEmailId) {
       this.studName = studName;
       this.studEmailId = studEmailId;
    }

    public int getStudId() {
       return this.studId;
    }

    public String getStudName() {
       return this.studName;
    }

    public String getStudEmailId() {
        return this.studEmailId;
    }

    private void setStudId(int studId) {
        this.studId = studId;
    }

    private void setStudName(String studName) {
        this.studName = stuName;
    }

    private void setStudEmailId(int studEmailId) {
        this.studEmailId = studEmailId;
    }

}

2. JPA implementaion of Hibernate

package com.expt.hibernate.jpa;

import java.io.Serializable;

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

@Entity
@Table(name = "Student_Info")
public final class Student implements Serializable {

  @Id
  @GeneratedValue
  @Column(name = "STUD_ID", length = 5)
  private int studId;

  @Column(name = "STUD_NAME", nullable = false, length = 25)
  private String studName;

  @Column(name = "STUD_EMAIL", nullable = true, length = 30)
  private String studEmailId;

  public Student(final String studName, final String studEmailId) {
     this.studName = studName;
     this.studEmailId = studEmailId;
  }

  public int getStudId() {
     return this.studId;
  }

  public String getStudName() {
     return this.studName;
  }

  public String getStudEmailId() {
     return this.studEmailId;
  }

Also, I have provided the DB configuration properties in the associated hibernate-cfg.xml [in case of hibernate core] and persistence.xml [in case of JPA (hibernate entity manager)].

create a driver and perform

1. add a student and

2. query for the list of students and print their details.

Then the issue comes when you run the driver program.

Hibernate core - output

Exception in thread "main" org.hibernate.InstantiationException: No default constructor for entity: com.expt.hibernate.core.Student at org.hibernate.tuple.PojoInstantiator.instantiate(PojoInstantiator.java:84) at org.hibernate.tuple.PojoInstantiator.instantiate(PojoInstantiator.java:100) at org.hibernate.tuple.entity.AbstractEntityTuplizer.instantiate(AbstractEntityTuplizer.java:351) at org.hibernate.persister.entity.AbstractEntityPersister.instantiate(AbstractEntityPersister.java:3604) ....

....

This exception is flashed when the driver is executed for the first time itself.

JPA Hibernate - output

First execution of the driver on a fresh DB provided the following output.

DEBUG SQL:111 - insert into student.Student_Info (STUD_EMAIL, STUD_NAME) values (?, ?) 17:38:24,229 DEBUG SQL:111 - select student0_.STUD_ID as STUD1_0_, student0_.STUD_EMAIL as STUD2_0_, student0_.STUD_NAME as STUD3_0_ from student.Student_Info student0_

1 || Jegan || [email protected]

second execution of the driver provided the following output.

DEBUG SQL:111 - insert into student.Student_Info (STUD_EMAIL, STUD_NAME) values (?, ?) 17:40:25,254 DEBUG SQL:111 - select student0_.STUD_ID as STUD1_0_, student0_.STUD_EMAIL as STUD2_0_, student0_.STUD_NAME as STUD3_0_ from student.Student_Info student0_

....

Could anyone please let me know if you have encountered this sort of inconsistency?

Also, could anyone please let me know if the issue is a missing implementation with JPA-Hibernate?

~ Jegan