Mapping dictionary - nhibernate

Question

I have 3 tables Users, AccessLevels, Roles. My User class have public virtual Dictionary<Role,AccessLevel> Roles {get; set;}, and
Role class have public virtual Dictionary<User,AccessLevel> Users {get;set;} ? How such dictionaries should be represented in the mapping?

Answer 1

in FluentNhibernate it would look like
HasManyToMany(user => user.Roles)
.Table("UserRoleAccessLevel")
.AsEntityMap("role_id")
.KeyColumn("user_id");
HasManyToMany(role => role.Users)
.Table("UserRoleAccessLevel")
.AsEntityMap("user_id")
.KeyColumn("role_id");
can't test it right now though
Update: in hbm.xml
<map name="Roles" table="UserRoleAccessLevel">
<key column="user_id" />
<index-many-to-many class="Role" column="role_id" />
<many-to-many class="AccessLevel" column="accesslevel_id" />
</map>
<map name="Users" table="UserRoleAccessLevel">
<key column="role_id" />
<index-many-to-many class="User" column="user_id" />
<many-to-many class="AccessLevel" column="accesslevel_id" />
</map>

Answer 2

It would be very nice if you provided structure of your tables, especially AccessLevels table. As far as I could guess structure of your tables I can suggest you this mapping
<class name="User" table="Users">
<id name="Id" column="user_id">
<generator class="native" />
</id>
<property name="Name" column="user_name" not-null="true" />
<map name="Roles" table="AccessLevels" cascade="save-update">
<key column="user_id" />
<map-key-many-to-many column="role_id" class="Role" />
<one-to-many class="AccessLevel"/>
</map>
</class>
<class name="Role" table="Roles">
<id name="Id" column="role_id">
<generator class="native" />
</id>
<property name="Name" column="user_name" not-null="true" />
</class>
<class name="AccessLevel" table="AccessLevels">
<id name="Id" column="Id">
<generator class="native" />
</id>
<property name="Level" column="level" not-null="true" />
<many-to-one name="User" column="user_id" not-null="true" cascade="save-update" />
<many-to-one name="Role" column="role_id" not-null="true" cascade="save-update" />
</class>