question to many-to-many of hibernate

From:

"Michael Plate" <michael.plate3@ewetel.net>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 8 May 2007 23:03:15 +0200

Message-ID:

<f1qojk$nv0$1@news1.ewetel.de>

hello

i have three db tables and the first two tables contains the masterdatas.
last table is a mapping table for the both masterdata tables.

CREATE TABLE IF NOT EXISTS MASTERDATA_NO1
(
   id bigint not null,
   description varchar(255) not null,
   primary key (id)
);

CREATE TABLE IF NOT EXISTS MASTERDATA_NO2
(
   id bigint not null,
   description varchar(255) not null,
   value int not null,
   primary key (id)
);

CREATE TABLE IF NOT EXISTS MAPPING_MD1_MD2
(
   FK_MD1_ID bigint not null,
   FK_MD2_ID bigint not null,
   primary key (FK_MD1_ID, FK_MD2_ID)
);

my mapping file for hibernate is
.....
  <class name="Masterdata1" table="masterdata_no1" >

    <id name="id" column="id">
   <generator class="increment"/>
  </id>

  <property name="description" column="description" />

  <set name="md2" table="mapping_md1_md2">
   <key column="FK_MD1_ID"/>
   <many-to-many class="Masterdata2" column="FK_MD2_ID" />
  </set>

  </class>
...

my java classes are ...

package at.plate.michael.hibernate.valueobject;

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

public class Masterdata1 {
//properties
private int id;
private String description;
private Set<Masterdata2> md2 = new HashSet<Masterdata2>();

//getter and setter for properties
public String getDescription() { return description; }
public int getId() { return id; }
public void setDescription(String description) { this.description =
description; }
public void setId(int id) { this.id = id; }
public Set<Masterdata2> getMd2() { return md2; }
public void setMd2(Set<Masterdata2> md2) { this.md2 = md2; }
}

.... and ...

package at.plate.michael.hibernate.valueobject;

public class Masterdata2 {
//properties
private int id;
private String description;
private int value;

//getter and setter for properties
public String getDescription() { return description; }
public int getId() { return id; }
public void setDescription(String description) { this.description =
description; }
public void setId(int id) { this.id = id; }
....
}

at the moment this runs without a problem. i can store and load Masterdata1
objects with sets of Masterdata2 objects about hibernate to/from database.

yet, i moved the property field 'value' from Masterdata2 to Mapping-Table
and this content should be inserted in masterdata2 object.

how i can modify the mapping file of hibernate to solved this problem?

many thanks and best regards
Michael Plate