Hi,

Hibernate version:3.1

In our project we have the requirement to develop a Custom Id Generator
which should be of type String and the value in the column of the table
with the name of the table and Id generated by the sequence.

For Example: -
If name of the table is EMP the values in the Empno should go as EMP_100,
EMP_101, EMP_102 so on.


Actually once I found the code in net when I was searching long back while doing some RnD. Now I dont have the URL. If anybody knows any such URLs pls let me know.

Thanks in Advance.

Manjith A.

Hi,

1. Some usefull links:

http://forum.hibernate.org/viewtopic.ph ... rgenerator

http://forum.hibernate.org/viewtopic.ph ... rgenerator

2. A implemntation of what you need is:

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 "EMP";
}
}

Enjoy.

Hi,

Thanks For the solution.

I will try with the same and let you know if any issues.

I would be grateful to you If you can can tell me how do you map the
Identifier property in .hbm.xml if it differs from the normal id mapping.

Thanks
Manjith A

Hello again,

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