NHibernate bidirectional many-to-many association - nhibernate

Question

I have a class with following description:
public class Customer {
public ISet<Client> Contacts { get; protected set;}
}
I want to map Contacts property onto following table:
CREATE TABLE user_contacts (
user1 uuid NOT NULL,
user2 uuid NOT NULL
)
I want it to map bidirectionally, i.e. when Customer1 added to Customer2's Contacts, Customer1's Contacts collection should contain Customer2 (maybe only after entity reload). How could I do that?
Update Sure I can map left-to-right and right-to-left sets and then combine then at runtime, but it'll... hmm... untasty... Is there other solution? Any way, thank you very match, FryHard!

Answer 1

Take a look at this link on what hibernate calls unidirectional many-to-many associations. In Castle ActiveRecord I make use of HasAndBelongsToMany links, but I am not sure how exactly it is mapped in nhibernate.
Though taking a look at your question a little deeper, it looks like you will be linking bidirectionally from customer to user_contacts, which could break the many-many link. I will play with an example and see what I can come up with.
An Export of the hbm files from ActiveRecord shows this
<?xml version="1.0" encoding="utf-16"?>
<hibernate-mapping auto-import="true" default-lazy="false" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="urn:nhibernate-mapping-2.2">
<class name="NHibernateMapping.Customer, NHibernateMapping" table="Customer" schema="dbo">
<id name="Id" access="property" column="Id" type="Int32" unsaved-value="0">
<generator class="identity">
</generator>
</id>
<property name="LastName" access="property" type="String">
<column name="LastName" not-null="true"/>
</property>
<bag name="ChildContacts" access="property" table="user_contacts" lazy="false">
<key column="user1" />
<many-to-many class="NHibernateMapping.Customer, NHibernateMapping" column="user2"/>
</bag>
<bag name="ParentContacts" access="property" table="user_contacts" lazy="false" inverse="true">
<key column="user2" />
<many-to-many class="NHibernateMapping.Customer, NHibernateMapping" column="user1"/>
</bag>
</class>
</hibernate-mapping>
ActiveRecord example:
[ActiveRecord("Customer", Schema = "dbo")]
public class Customer
{
[PrimaryKey(PrimaryKeyType.Identity, "Id", ColumnType = "Int32")]
public virtual int Id { get; set; }
[Property("LastName", ColumnType = "String", NotNull = true)]
public virtual string LastName { get; set; }
[HasAndBelongsToMany(typeof(Customer), Table = "user_contacts", ColumnKey = "user1", ColumnRef = "user2")]
public IList<Customer> ChildContacts { get; set; }
[HasAndBelongsToMany(typeof(Customer), Table = "user_contacts", ColumnKey = "user2", ColumnRef = "user1", Inverse = true)]
public IList<Customer> ParentContacts { get; set; }
}
Hope it helps!