Hi,
I am facing a problem in Hibernate cascade update. I have a Customer with a mapping set of Pieces (with CustomerPiece-mapping in the middle)

Customer.hbm.xml:
...
...
<set name="pieces" table="customer_piece" lazy="true">
<key column="customer_id" />
<many-to-many column="piece_id" class="fi.saha.hibernate.Piece" />
</set>

CustomerPiece.hbm.xml:
...
...
<many-to-one name="customer" class="fi.saha.hibernate.Customer" insert="false" update="false" column="customer_id" />

So the DB-structure goes like customer=>customer_piece=>piece.

When I try to update the customer instance with a new set of Pieces, Hibernate first deletes all the rows from customer_piece -table and then inserts them again (see the generated SQL below).
CustomerPiece -table holds valuable information for our software and thus all the rows must not be deleted from that table at the beginning of the update.

How can I prevent Hibernate from deleting all the rows at first from "customer_piece" in the cascade update and instead only delete those not in the updated Set and add the new ones?


regards,
Jari Laitinen


Hibernate version:
3.0

Name and version of the database you are using:
MySQL 5.0

The generated SQL (show_sql=true):
15:29:23,484 INFO [STDOUT] Hibernate: update customer set NAME=?, PASSWORD=?, PIECE_LIMIT=?, DATABASE_NAME=?, ACTIVE=?, LAST_VISIT=?, TYPE=?, START_DATE=?, END_DATE=?, CUSTOMER=?, VERSION=?, CONTACT=?, STREETADDRESS=?, POSTALADDRESS=?, INFO=?, INFO2=?, GSM=?, PHONE=?, EMAIL=?, ONLINE_ORDER=?, LOGGED=?, DATE_UPDATED=?, UPDATE_FLAG=?, EXTRANET_PASSWORD=?, HALT_FLAG=? where ID=?
15:29:23,484 INFO [STDOUT] Hibernate: delete from customer_piece where customer_id=?
15:29:23,500 INFO [STDOUT] Hibernate: insert into customer_piece (customer_id, piece_id) values (?, ?)
etc...
etc...

Hi Jari,

to me it seems your association should be many-to-many ;-)

In your mapping the CustomerPiece table has to primary key (id), so how should Hibernate do tupel operations? You map a set and Hibernate does a set operation (delete all, insert). You can add id column to CustomerPiece table and tell Hibernate that there is one (<idbag>).

But maybe many-to-many is your choice.

-Thomas

Hi Jari,

to me it seems your association should be many-to-many ;-)

In your mapping the CustomerPiece table has to primary key (id), so how should Hibernate do tupel operations? You map a set and Hibernate does a set operation (delete all, insert). You can add id column to CustomerPiece table and tell Hibernate that there is one (<idbag>).

But maybe many-to-many is your choice.

-Thomas

Hi Thomas and thanks for your reply although I didn't quite get it ;)

Below you can find the full mapping of the CustomerPiece.hbm.xml

Could there be a way to tell Hibernate to only add the missing rows to db and delete the rows from db not found in the Set of Piece-instances when updating the Customer directly?
(Customer.hbm.xml was in the first post of this topic)


<class
name="fi.saha.hibernate.CustomerPiece"
table="customer_piece"
>
<id name="id"
type="java.lang.Integer"
column="id">
<generator class="native" />
</id>
<property
name="pieceId"
type="int"
column="piece_id"
not-null="true"
length="11"/>

<property
name="customerId"
type="int"
column="customer_id"
not-null="true"
length="11"
/>

....
... some properties here in between not related to the problem but
... contain valuable information to the software
....

<!-- Associations -->

<many-to-one name="customer" class="fi.saha.hibernate.Customer" insert="false" update="false" column="customer_id" />
<many-to-one name="piece" class="fi.soittorasia.saha.hibernate.Piece" insert="false" update="false" column="piece_id"/>

Hi Jari,

that's exactly was Hibernate does with many-to-many:

10:13:23,546 DEBUG org.hibernate.SQL: delete from customer_piece where customer_id=? and piece_id=?
Hibernate: delete from customer_piece where customer_id=? and piece_id=?
10:13:23,546 DEBUG org.hibernate.jdbc.AbstractBatcher: preparing statement
10:13:23,562 DEBUG org.hibernate.type.LongType: binding '1' to parameter: 1
10:13:23,562 DEBUG org.hibernate.type.LongType: binding '3' to parameter: 2
10:13:23,562 DEBUG org.hibernate.persister.collection.AbstractCollectionPersister: done deleting collection rows: 1 deleted

As you can see, after deleting one piece from Set, Hibernate deletes the tupel from relation table customer_piece.

Here is a complete sample:


Customer.java:

package forum.jari;

import java.util.HashSet;
import java.util.Set;

public class Customer {
private long id;
private String name;
private Set<Piece> pieces = new HashSet<Piece>();


public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Set<Piece> getPieces() {
return pieces;
}
public void setPieces(Set<Piece> pieces) {
this.pieces = pieces;
}



}


Piece.java:

package forum.jari;

public class Piece {
private long id;
private String name;



public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}

}


JariMain.java:

package forum.jari;

import java.util.Iterator;
import java.util.List;
import java.util.Set;

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

public class JariMain {

private SessionFactory factory;

public static void main(String[] args) throws Exception {

final JariMain jari = new JariMain();

Configuration cfg = new Configuration()
.configure()
.addClass(Customer.class)
.addClass(Piece.class)
.setProperty(Environment.HBM2DDL_AUTO, "create");

cfg.setProperty("hibernate.show_sql", "true");


jari.factory = cfg.buildSessionFactory();

jari.createData();

jari.listData();

jari.changeSet();

}

private void changeSet() {

Session s = factory.openSession();
Transaction tx = s.beginTransaction();

List<Customer> list = s.createCriteria(Customer.class).list();
for (Customer c : list) {
System.out.println("Change Set of pieces for Customer: " + c.getName());
Set pieces = c.getPieces();
Iterator it = pieces.iterator();
it.next(); // goto first item
it.remove(); // remove it
System.out.println("***");
}

tx.commit();
s.close(); // we'll be save now


}

private void listData() {
Session s = factory.openSession();
Transaction tx = s.beginTransaction();

List<Customer> list = s.createCriteria(Customer.class).list();
for (Customer c : list) {
System.out.println("Customer: " + c.getName());
for (Piece p : c.getPieces()) {
System.out.println(" Piece: " + p.getId() + " , " + p.getName());
}
System.out.println("---");
}

tx.commit();
s.close();

}

private void createData() {
Session s = factory.openSession();
Transaction tx = s.beginTransaction();

Customer c = new Customer();
c.setName("Customer1");


Piece p1 = new Piece();
p1.setName("Piece1");
c.getPieces().add(p1);

Piece p2 = new Piece();
p2.setName("Piece2");
c.getPieces().add(p2);

s.save(c);

tx.commit();
s.close();

}


}

Customer.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="forum.jari">

<class name="Customer" table="customer" lazy="true">
<comment>Customer</comment>

<id name="id">
<generator class="native"/>
</id>

<property name="name"
not-null="true"
length="80"
column="name"/>


<set name="pieces" table="customer_piece" lazy="true" cascade="save-update">
<key column="customer_id" />
<many-to-many column="piece_id" class="Piece" />
</set>


</class>

</hibernate-mapping>


Piece.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="forum.jari">

<class name="Piece" table="piece" lazy="true">
<comment>Piece</comment>

<id name="id">
<generator class="native"/>
</id>


<property name="name"
not-null="true"
length="80"
column="name"/>


</class>

</hibernate-mapping>



-Thomas

Thanks very much for your testing!

So I guess the main point here is that I should always modify the existing Set of Pieces in the Customer instance and never set the entire Set of Pieces at once if I want Hibernate to only add the added ones and remove the removed ones.