I have a many-to-many relationship set up where a User can have many Roles and many Users can have the same Role. Do I need to make the relationship bidirectional to query Users by Role?

For example, given a Role's id, I'd like to get a list of the Users that have that Role. My application is already written, so I'd prefer not to have to go back and make the relationship bidirectional just for this query.

Thanks,
Brian


Hibernate version:
2.1.6

Mapping documents:

User.hbm.xml:
<hibernate-mapping>
<class name="com.briankuhn.vocab.data.value.User" table="users">
<id name="id" column="id" unsaved-value="0">
<generator class="increment"/>
</id>
<property name="name" column="name" not-null="true"/>
<property name="password" column="password" not-null="true"/>
<set name="roles" table="user_roles" cascade="save-update">
<key column="user_id"/>
<many-to-many class="com.briankuhn.vocab.data.value.Role" column="role_id"/>
</set>
</class>
</hibernate-mapping>

Role.hbm.xml
<hibernate-mapping>
<class name="com.briankuhn.vocab.data.value.Role" table="roles">
<id name="id" column="id" unsaved-value="0">
<generator class="increment"/>
</id>
<property name="name" column="name" not-null="true"/>
</class>
</hibernate-mapping>


Code between sessionFactory.openSession() and session.close():
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Full stack trace of any exception that occurs:
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Name and version of the database you are using:
hsqldb vX.X

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Users belong to many Roles.
Roles contain many Users.

I want to be able to find all Users that belong to Role x.
I want to be able to find all Roles that contain User y.

Will a unidirectional mapping (like the one below) work, or do I need to make the relationship bidirectional?

If I can keep it unidirectional, what would the HQL query look like?

Thanks,
Brian

you can keep it unidirectionnal
(also be carefull with word "user")

"select elements(user.roles) from Uzer user where uzer.id = "

or "select uzer from User uzer, Role role
where role.xxx = yyyy
and role in elements(uzer.roles"

I came cross a similiar situation using Critiera API. How can I make it work with Criteria API?

unidirectional mapping like A(1) ---> B(*), I am trying to query B by giving A. Since there is no association to A in B, how can I construct my Criteria for B?

Thanks,
zeng