I have some difficulty to find the right solution for the mapping problem I have here.

I have a User class which has two business methods: getCoWorkers() and getDirectCoWorkers(). Direct co-workers are a subset of co-workers. Both methods return a collection of User objects. The relationship between users and co-workers is many-to-many, and it's unidirectional from users to co-workers. Since direct co-workers are co-workers, I don't want to keep two copies of the same user in the object.

The table of the relationship is like:

id (synthetic primary key)
user_id
co_worker_id
co_worker_flag (indicating whether this co-worker is a direct co-worker)

Anyone can help out on this?

Thanks in advance.

Why not make the getDirectCoWorkers() a transient method?

You can use your getCoWorkers() to return the set of coworkers with the flag, then DirectCoWorkers can just filter that collection and return the subset.

Will the following code work based on the suggestion?

public User()
{
}


pubic CoWorkerRelationship
{
private User user;
private User coWorker;
private String directCoWorkerFlag = "N";
}


In User.hbm.xml use this to map the relationship:

<set name="coWorkers" lazy="true" table="co_worker_relationship">
<key column="user_id">
<composite-element class="CoWorkerRelationship">
<parent name="User">
<many-to-one name="coWorker" class="User" column="co_worker_id" not-null="true"/>
<property name="directCoWorkerFlag" column="co_worker_flag" not-null="true"/>
</composite-element>
</set>