Hello.
I have problems writing my mapping file. Here is my situation :
I have a table T_CONTRACT and a table T_CLIENT. T_CONTRACT is containing an id of T_CLIENT (representing the subsriber).
I would like to make a join between those 2 table so that i can get something like

so far, i get to write this :
Contract.hbm.xml

Client.hbm.xml

But it doesn't work at all (a sql syntax exception is raised)
Can someone help me please ?

Could you share the Exception ?

-Gayatri

javax.servlet.ServletException: org.hibernate.exception.SQLGrammarException: could not execute query

I dont think it's really relevant of my problem. Does anybody have a <join> example to gave me ? :(
The ones of the hibernate documentation are not so helpy to me

I have been trying this :
I obtain this sql :
It's almost it, but it seems that Hibernate join automatically the id of the curent table (T_CONTRACT) but i need to join my table from an another id named ID_PERSON, so I could get :
How can i set that ?

Hi. I think you misunderstood the join-table part. It is the table(other than client and contract) which maps the contract ids to client ids. For example:

Contract.java

public class Contract {
private int id;
private Client fkSubscriber;
public void setId(int id){
this.id = id;
}
public void setFkSubscriber(Client fkSubscriber){
this.fkSubscriber = fkSubscriber;
}
public int getId(){
return id;
}
public Client getFkSubscriber(){
return fkSubscriber;
}
}

The xml mapping file for Contract(Contract.hbm.xml) will be:

<?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>

<class name="Contract" table="CONTRACT">
<id name="id" column="ID" type="int" >
<generator class="increment"/>
</id>

<join table="CONT_CLIENT" optional="true" >
<key column="ID" unique="true"/>
<many-to-one name="fkSubscriber" column="CLIENT" not-null="true"/>
</join>
</class>
</hibernate-mapping>

The name of the table given in<join table...> is the name of the new table that maps contracts to clients.

here are the other files:
Client.java

public class Client {
private int id;
private String fullName;
public void setId(int id){
this.id = id;
}
public void setFullName(String fullName){
this.fullName = fullName;
}
public int getId(){
return id;
}
public String getFullName(){
return fullName;
}
}

Client.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 >
<class name="Client" table="CLIENT">
<id name="id" type="int">
<column name="ID" />
<generator class="increment" />
</id>
<property name="fullName" type="java.lang.String" column="FNAME"/>
</class>
</hibernate-mapping>

A file called "Loader.java" that inserts and retrieves the list of contracts.


import java.util.*;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class Loader {
public static void main(String[] args) {
Configuration cfg = new Configuration();
cfg.configure("hibernate.cfg.xml");
SessionFactory sessionFactory = cfg.buildSessionFactory();

Session session1 = sessionFactory.getCurrentSession();
session1.beginTransaction();

Contract con1 = new Contract();
Contract con2 = new Contract();
Contract con3 = new Contract();
Client clnt1 = new Client();
Client clnt2 = new Client();
clnt1.setFullName("client 1");
clnt2.setFullName("client 2");
session1.save(clnt1);
session1.save(clnt2);
con1.setFkSubscriber(clnt1);
con2.setFkSubscriber(clnt1);
con3.setFkSubscriber(clnt2);

session1.save(con1);
session1.save(con2);
session1.save(con3);


session1.getTransaction().commit();
Session session2 = sessionFactory.getCurrentSession();
session2.beginTransaction();
List<Contract> conts = session2.createQuery("from Contract").list();
System.out.println("the size of the list of contracts is " + conts.size());
for(Object m : conts){
Contract loadedContract = (Contract) m;
System.out.println(loadedContract.getId() +"\t" + loadedContract.getFkSubscriber().getFullName());

}
session2.getTransaction().commit();

}
}

For SQl part:
create table contract(id int not null);
create table client(id int not null, fname char(255));
create table cont_client(id int not null, client int not null);

I hope you got ideas now. If there's any question feel free to post it.

Thanks.

Do not forget to rate the post!!!

Hi,
Thanks for your reply. I think i got what you try to explain to me.
But the example you gave me do not what i'm expecting.
I would like to join my table contract with a person, with respectively the id CONTRACT.ID_PERSON and PERSON.ID. So that hibernate create a object of type Person named fkSubscriber each time it fetch a row of Contract.
I hope it's more clear now.

I think I got your problem. But just to make sure can you please specify what your classes are and what constitutes these classes?

Try using <key property-ref="...."...>

This link might help you.

http://www.redhat.com/docs/manuals/jboss/jboss-eap-4.2/doc/hibernate/Hibernate_Reference_Guide/Mapping_declaration-key.html

Thanks.