Delete Row from MySql Table using Hibernate - mysql

Question

Hello i am a fresher i just took i application from online was trying to run it parameters i am using is
Maven
SpringMVC
Mysql
Java
Eclipse
i am able to create a table in the database with this code and delet also but when i am trying to dete it withoutr using save option it's giving me error
****org.hibernate.event.def.DefaultDeleteEventListener deleteTransientEntity
INFO: handling transient entity in delete processing****
when i checked online it show to get the object of the row in the app.java page then delete that object to delete the row i don't know how to get that object and how to pass the row of the database in that object(how to get that field mbedded into the object and how to get that object)plz help all i want is to delete a row from the database base on some column name specific value
App.java class
package com.mkyong.common;
import org.hibernate.Session;
import com.mkyong.persistence.HibernateUtil;
public class App
{
public static void main( String[] args )
{
System.out.println("Maven + Hibernate + MySQL");
Session session = HibernateUtil.getSessionFactory().openSession();
session.beginTransaction();
Stock stock = new Stock();
stock.setStockCode("4715");
stock.setStockName("GENM");
stock.getStockCode();
stock.getStockName();
//session.save(stock);
session.delete(stock);
session.getTransaction().commit();
}
}
AppTest.java
package com.mkyong.common;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
/**
* Unit test for simple App.
*/
public class AppTest
extends TestCase
{
/**
* Create the test case
*
* #param testName name of the test case
*/
public AppTest( String testName )
{
super( testName );
}
/**
* #return the suite of tests being tested
*/
public static Test suite()
{
return new TestSuite( AppTest.class );
}
/**
* Rigourous Test :-)
*/
public void testApp()
{
assertTrue( true );
}
}
Stock.java
package com.mkyong.common;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import static javax.persistence.GenerationType.IDENTITY;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;
#Entity
#Table(name = "stock", catalog = "gagan", uniqueConstraints = {
#UniqueConstraint(columnNames = "STOCK_NAME"),
#UniqueConstraint(columnNames = "STOCK_CODE") })
public class Stock implements java.io.Serializable {
private Integer stockId;
private String stockCode;
private String stockName;
public Stock() {
}
public Stock(String stockCode, String stockName) {
this.stockCode = stockCode;
this.stockName = stockName;
}
#Id
#GeneratedValue(strategy = IDENTITY)
#Column(name = "STOCK_ID", unique = true, nullable = false)
public Integer getStockId() {
return this.stockId;
}
public void setStockId(Integer stockId) {
this.stockId = stockId;
}
#Column(name = "STOCK_CODE", unique = true, nullable = false, length = 10)
public String getStockCode() {
return this.stockCode;
}
public void setStockCode(String stockCode) {
this.stockCode = stockCode;
}
#Column(name = "STOCK_NAME", unique = true, nullable = false, length = 20)
public String getStockName() {
return this.stockName;
}
public void setStockName(String stockName) {
this.stockName = stockName;
}
}
HibernateUtil.java
package com.mkyong.persistence;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
public class HibernateUtil {
private static final SessionFactory sessionFactory = buildSessionFactory();
private static SessionFactory buildSessionFactory() {
try {
// Create the SessionFactory from hibernate.cfg.xml
return new AnnotationConfiguration().configure().buildSessionFactory();
}
catch (Throwable ex) {
// Make sure you log the exception, as it might be swallowed
System.err.println("Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
public static void shutdown() {
// Close caches and connection pools
getSessionFactory().close();
}
}
hibernatecfg.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database connection settings -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<!-- Database connection settings -->
<!-- UAT Database connection settings -->
<property name="connection.url">jdbc:mysql://localhost:3306/gagan</property>
<property name="connection.username">root</property>
<property name="connection.password">123456</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="show_sql">true</property>
<property name="hibernate.hbm2ddl.auto">update</property>
<!-- Think Before made any change in below flag may that clean you complete database -->
<mapping class="com.mkyong.common.Stock"></mapping>
</session-factory>
</hibernate-configuration>
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.mkyong.common</groupId>
<artifactId>HibernateExample</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>HibernateExample</name>
<url>http://maven.apache.org</url>
<repositories>
<repository>
<id>JBoss repository</id>
<url>http://repository.jboss.com/maven2/</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<!-- MySQL database driver -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.9</version>
</dependency>
<!-- Hibernate core -->
<dependency>
<groupId>hibernate</groupId>
<artifactId>hibernate3</artifactId>
<version>3.2.3.GA</version>
</dependency>
<!-- Hibernate annotation -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>4.3.5.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-c3p0</artifactId>
<version>4.3.5.Final</version>
</dependency>
<!-- Hibernate library dependecy start -->
<dependency>
<groupId>dom4j</groupId>
<artifactId>dom4j</artifactId>
<version>1.6.1</version>
</dependency>
<dependency>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
<version>1.1.1</version>
</dependency>
<dependency>
<groupId>commons-collections</groupId>
<artifactId>commons-collections</artifactId>
<version>3.2.1</version>
</dependency>
<dependency>
<groupId>cglib</groupId>
<artifactId>cglib</artifactId>
<version>2.2</version>
</dependency>
<!-- Hibernate library dependecy end -->
</dependencies>
</project>
[1]: http://i.stack.imgur.com/tkv2h.png

Answer 1

You can not delete transient object. You need to first synchronize the object with the database. For example you got id of your stock component. Here is a sample piece of code to delete the object based on stockId. Even when you create an object using hibernate it return ID. Use this ID to delete the row from database.
Session session = HibernateUtil.getSessionFactory().openSession();
try {
session.beginTransaction();
Serializable id = stockId;
Object persistentInstance = session.load(Stock.class, id);
if (persistentInstance != null) {
session.delete(persistentInstance);
session.getTransaction().commit();
System.out.println ("Deleted Sucessfully");
}
else {
System.out.println ("Did not find the Stock Object in persistance");
}
}
catch (HibernateException e) {
e.printStackTrace();
}
finally {
if(session!=null){
session.close();
}
}

Answer 2

Stock object is in Transient state ,to delete it, it should be persist in database also note that when you try to delete any object its primary key should be set with it otherwise it will not reflect any changes into the database as STOCK_ID is primary key here .