Hi ,
i have a user class ,it consists one is id as string type and another one is name which is also string type my data base table name is sampleTest , i have to generate id in db2 database which is this formate abc1, abc2,abc3 .... like this only , please tell me how can i implement , if any body solve my problem thanks to advance...waiting eagerly to reply ...

Thanks & Regards

Sandeep narela

You can implement your own generator, just implement IdentifierGenerator and in the Mapping file specify like this:

<id name="id" type="string" column="string_id">
<generator class="org.hibernate.YourCustomGenerator">
</generator>
</id>

You can have a look in the hibernate documentation (5.1.4 id).

Hi Dear Stefan,

my concern to generate id like this ABC1, ABC2,ABC3....
in hiberrnate doc 5.1.4 only generate numeric number i want to generate alphnumeric number ,if u could provide me complete solution , i would be greatful to u.eagerly waiting to your reply.this is essentially need in my project and i have to implement so please give the complete way,so that i would be able to do implement id like ABC1,ABC2..... .

Thanks & Regards
sandeep

your generator class looks something like this:

public class AlphaNumericGenerator implements IdentifierGenerator {

public Serializable generate(SessionImplementor session, Object object) throws HibernateException {
// implement your algorithm, e.g. you could select max(id) from your_table and add 1

return "ABC1";
}

}


and in the mapping specify <id>...<generator class=AlphaNumericGenerator>

thats all ;-)

Here is your generator:

import java.io.Serializable;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.hibernate.HibernateException;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.exception.JDBCExceptionHelper;
import org.hibernate.id.IdentifierGenerator;
import org.hibernate.id.PersistentIdentifierGenerator;

public class MyGenerator implements IdentifierGenerator {

String sql = "select next from dual";

public Serializable generate(SessionImplementor session, Object object)
throws HibernateException {
return new String(getText().concat(getNext(session)));
}

private String getNext(SessionImplementor session) {
long next;

Connection conn = session.connection();

try {
PersistentIdentifierGenerator.SQL.debug(sql);
PreparedStatement st = conn.prepareStatement(sql);
ResultSet rs = null;
try {
rs = st.executeQuery();
if (rs.next()) {
next = rs.getLong(1) + 1;
if (rs.wasNull())
next = 1;
} else {
next = 1;
}
sql = null;
} finally {
if (rs != null)
rs.close();
st.close();
}

} catch (SQLException sqle) {
throw JDBCExceptionHelper.convert(session.getFactory()
.getSQLExceptionConverter(), sqle,
"could not fetch initial value", sql);
}

return new Long(next).toString();
}

public String getText() {
return "ABC";
}
}

Of course:

<id name="id" type="string" column="string_id">
<generator class="MyGenerator">
</generator>
</id>

like stefan_f suggested.

[quote="TOMBATLECRUISEr"]Here is your generator:

import java.io.Serializable;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.hibernate.HibernateException;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.exception.JDBCExceptionHelper;
import org.hibernate.id.IdentifierGenerator;
import org.hibernate.id.PersistentIdentifierGenerator;

public class MyGenerator implements IdentifierGenerator {

String sql = "select next from dual";

public Serializable generate(SessionImplementor session, Object object)
throws HibernateException {
return new String(getText().concat(getNext(session)));
}

private String getNext(SessionImplementor session) {
long next;

Connection conn = session.connection();

try {
PersistentIdentifierGenerator.SQL.debug(sql);
PreparedStatement st = conn.prepareStatement(sql);
ResultSet rs = null;
try {
rs = st.executeQuery();
if (rs.next()) {
next = rs.getLong(1) + 1;
if (rs.wasNull())
next = 1;
} else {
next = 1;
}
sql = null;
} finally {
if (rs != null)
rs.close();
st.close();
}

} catch (SQLException sqle) {
throw JDBCExceptionHelper.convert(session.getFactory()
.getSQLExceptionConverter(), sqle,
"could not fetch initial value", sql);
}

return new Long(next).toString();
}

public String getText() {
return "ABC";
}
}

Of course:

<id name="id" type="string" column="string_id">
<generator class="MyGenerator">
</generator>
</id>

Hi dear,
i tried this code but given me error,i am sending my code to u.just check ,where i have to correction ?

******TestH .java**********
public class TestH {
private String next ;
private String text;

/**
* @return Returns the id.
*/

/**
* @param string
*/

/**
* @return Returns the next.
*/
public String getNext() {
return next;
}
/**
* @param next The next to set.
*/
public void setNext(String next) {
this.next = next;
}
/**
* @return Returns the text.
*/
public String getText() {
return text;
}
/**
* @param text The text to set.
*/
public void setText(String text) {
this.text = text;
}
}
############# this is my TestH.hbm.xml#########
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.test">

<class name="TestH" table="sampleTest" >
<id name="next" type="string">
<generator class="com.test.MyGenerator" >

</generator>
</id>
<property name="text" type="string" />
</class>

</hibernate-mapping>

*********This is my MyGenerator.java class************
package com.test;
import java.io.Serializable;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.hibernate.HibernateException;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.exception.JDBCExceptionHelper;
import org.hibernate.id.IdentifierGenerator;
import org.hibernate.id.PersistentIdentifierGenerator;

public class MyGenerator implements IdentifierGenerator {

String sql = "select next from sampleTest";

public Serializable generate(SessionImplementor session, Object object)
throws HibernateException {
return new String(getText().concat(getNext(session)));
}

private String getNext(SessionImplementor session) {
long next;

Connection conn = session.connection();

try {
PersistentIdentifierGenerator.SQL.debug(sql);
PreparedStatement st = conn.prepareStatement(sql);
ResultSet rs = null;
try {
rs = st.executeQuery();
if (rs.next()) {
next = rs.getLong(1) + 1;
if (rs.wasNull())
next = 1;
} else {
next = 1;
}
sql = null;
} finally {
if (rs != null)
rs.close();
st.close();
}

} catch (SQLException sqle) {
throw JDBCExceptionHelper.convert(session.getFactory()
.getSQLExceptionConverter(), sqle,
"could not fetch initial value", sql);
}

return new Long(next).toString();
}

public String getText() {
return "ABC";
}
}
%%%%%%%%%% This is my test porgram%%%%%%%%%

package com.test;

import org.hibernate.Session;
import org.hibernate.Transaction;

/**
* @author sandeepn
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code Style - Code Templates
*/
public class TestRun {
public static void main(String args[])
{
TestH testH = new TestH();
//testH.setNext("abc2");
testH.setText("dddd");
System.out.println("insideTestRun1");
Session session = HibernateSessionFactory.currentSession();
Transaction tx = session.beginTransaction();
System.out.println("insideTestRun2");
session.save(testH);
System.out.println("insideTestRun3");
tx.commit();
}
}

When i run this code i got this error just see dear...where i have take correactive action to do generate my alphanumeric id properly ,waiting eagerly to your reply ..... a lot of thanks in advance

&&&&&&&&&Error which i am getting to running test program&&&&&&&
insideTestRun1
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
insideTestRun2
Exception in thread "main" org.hibernate.exception.SQLGrammarException: could not fetch initial value
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:59)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at com.test.MyGenerator.getNext(MyGenerator.java:49)
at com.test.MyGenerator.generate(MyGenerator.java:20)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:85)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:184)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:173)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:69)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:481)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:476)
at com.test.TestRun.main(TestRun.java:33)
Caused by: com.ibm.db2.jcc.b.SqlException: DB2 SQL error: SQLCODE: -206, SQLSTATE: 42703, SQLERRMC: ID
at com.ibm.db2.jcc.b.co.e(co.java:1361)
at com.ibm.db2.jcc.b.co.a(co.java:984)
at com.ibm.db2.jcc.a.bd.g(bd.java:121)
at com.ibm.db2.jcc.a.bd.a(bd.java:42)
at com.ibm.db2.jcc.a.r.a(r.java:31)
at com.ibm.db2.jcc.a.bp.g(bp.java:103)
at com.ibm.db2.jcc.b.co.g(co.java:968)
at com.ibm.db2.jcc.b.cp.T(cp.java:1378)
at com.ibm.db2.jcc.b.cp.d(cp.java:1781)
at com.ibm.db2.jcc.b.cp.K(cp.java:316)
at com.ibm.db2.jcc.b.cp.executeQuery(cp.java:299)
at com.test.MyGenerator.getNext(MyGenerator.java:33)
... 10 more

Hi,

I think here is the problem. Are you sure this sql is returnign something?

String sql = "select next from sampleTest";

As far as I know it should be something like: "select hibernate_sequence.nextval from dual".

The sql I've provided was just a sample. In my application I get the next value from another table and I have a totally different sql.

Hope this solve your problem (and of course - rate if it's helpfull).