Hi, i have some problem with hibernate implementing a one-to-many relationship, when i want to populate the Sep in the class that hold the set of another objects, the problem is that the object are created with id value "null" and when are added to the Set only the first object is inserted the others not, one solution that i founded is modify the equals "method" of the entity adding other propertys plus the id to make the object diferent from the already inserted in the Set (i think that this is the problem), here we attach an excerpt of the hibernate's xml definition and a fragment of the source code. Perhaps there is something wrong in definition's xml or source code, or another way to do that, and not to modify the "equals" method,

I'm using hibernate version 2.1

Best Regards and Thanks for a very good job in hibernate, Rodney

xml definition:

<class name="com.rdk.infbank.bus.UserRole" table="user_roles">
<id name="id" column="ur_id" type="long" unsaved-value="null">
<generator class="increment"/>
</id>
<many-to-one name="user" class="com.rdk.infbank.bus.User" column="user_id"/>
<many-to-one name="role" class="com.rdk.infbank.bus.Role" column="role_id"/>
</class>

<class name="com.rdk.infbank.bus.User" table="users">
<id name="id" column="user_id" type="long" unsaved-value="null">
<generator class="increment"/>
</id>
<property name="name" column="user_name" type="string" length="15" not-null="true"/>
<property name="password" column="user_pass" type="string" length="15" not-null="true"/>
<property name="active" column="user_active" type="boolean" />
<set name="roles" cascade="all-delete-orphan" inverse="true" lazy="false">
<key column="user_id"/>
<one-to-many class="com.rdk.infbank.bus.UserRole"/>
</set>
</class>

source code:

User usr = (User) command;
usr.getRoles().clear();

for(int i=0; i<ids.length; i++) {
Role rol = (Role) rDao.loadObj(ids[i]);
UserRole ur = new UserRole();
ur.setRole(rol);
ur.setUser(usr);
ur.setRolename(rol.getName());
ur.setUsername(usr.getName());
usr.getRoles().add(ur); -> solamente se adiciona el primer elemento
}

See http://www.hibernate.org/109.html.

I understand that you're using id for equals(). Then if you put multiple new objects into a set only one of them will be found in the set (because java uses equals() to distinguish between elements in the set). Instead, use some other properties for equals(). Preferably ones that won't change, e.g. the timestamp when the object was created etc.

A good idea is to use the equals() and hashCode() builders provided in the jakarta commons-lang package, they are good.

The article on the hibernate web site help me understand the problem, the best solution in my opinion is rewrite the Equals and HashCode of the class, but the problem is that in several case we don't have fields in table that help us to build a reallly good Equals and HashCode method