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!