Fluent Nhibernate many-to-many issue - nhibernate

Question

I have three tables:
Person (Id, FirstName)
Organization (Id, Name)
PersonOrganization (PersonId, OrganizationId, Details) many-to-many table
When I first mapped this using Fluent NHibernate I did not have a details column in the PersonOrganization table and mapped this using HasManyToMany in the PersonMap and OrganizationMap (no need to create a PersonOrganization domain object or map). I could writethe following code:
Organization org = new Organization { Name = "org" };
People people = new People { FirstName = "firstname", Organization = org };
peopleRepository.Add(people); // ISession.Save(people)
unitOfWork.Commit(); // ITransaction.Commit()
NHhibernate happily committed the data to all three tables.
The issue comes up when I added the details column in the PersonOrganization table. After some research it turns out that I now have to create a new PersonOrganization domain object and map and setup a HasMany relationship for both Person and Organization. My updated model and maps below:
public class People
{
public People()
{
LinkToOrganization = new List<PeopleOrganization>();
}
public virtual int Id { get; set; }
public virtual string FirstName { get; set; }
public virtual IList<PeopleOrganization> LinkToOrganization { get; set; }
}
public class Organization
{
public Organization()
{
LinkToPeople = new List<PeopleOrganization>();
}
public virtual int Id { get; set; }
public virtual string Name { get; set; }
public virtual IList<PeopleOrganization> LinkToPeople { get; set; }
}
public class PeopleOrganization
{
public virtual People People { get; set; }
public virtual Organization Organization { get; set; }
public virtual string Details { get; set; }
}
public class PeopleMap : ClassMap<People>
{
public PeopleMap()
{
Id(p => p.Id);
Map(p => p.FirstName).Length(100);
HasMany(x => x.LinkToOrganization)
.Table("PeopleOrganization")
.KeyColumn("PeopleId")
.AsBag()
.Inverse();
}
}
public class OrganizationMap : ClassMap<Organization>
{
public OrganizationMap()
{
Id(p => p.Id);
Map(p => p.Name).Length(50);
HasMany(x => x.LinkToPeople)
.Table("PeopleOrganization")
.KeyColumn("OrganizationId")
.AsBag()
.Inverse();
}
}
public class PeopleOrganizationMap : ClassMap<PeopleOrganization>
{
public PeopleOrganizationMap()
{
CompositeId()
.KeyReference(p => p.People, "PeopleId")
.KeyReference(p => p.Organization, "OrganizationId");
Map(p => p.Details).Length(100);
}
}
I now have to write the following code:
People people = new People { FirstName = "firstname" };
Organization org = new Organization { Name = "org" };
PeopleOrganization po = new PeopleOrganization { People = people, Organization = org, Details = "details" };
peopleRepository.Add(people); // ITransaction.Begin() ISession.Save(people)
organizationRepository.Add(org); // ISession.Save(org)
peopleOrganizationRepository.Add(po); // ISession.Save(po)
unitOfWork.Commit(); // ITransaction.Commit()
My questions are:
Are my mappings correctly setup to support this kind of many-to-many scenario?
Is there are way for me to just be able to do the following (which would write to all three tables):
-
People people = new People { FirstName = "firstname" };
Organization org = new Organization { Name = "org" };
PeopleOrganization po = new PeopleOrganization { People = people, Organization = org, Details = "details" };
peopleRepository.Add(people); // Just ONE ISession.Save(people)
unitOfWork.Commit(); // ITransaction.Commit()
Any input is highly appreciated.
Thanks

Answer 1

Firstly, you'll need to add your newly created PeopleOrganization to the collection on both entities (Organization and People). Then if you add a Cascade.All() to your HasMany chain, the saves should propagate (cascade) down to the PeopleOrganization and subsequently to Organization.
As a purely semantic suggestion, I'd recommend encapsulating the PeopleOrganization creation into a method on Person. Something like this:
class Person
{
public void AddOrganization(Organization org, string details)
{
var link = new PeopleOrganization { ... };
LinkToOrganization.Add(link)
org.LinkToPeople.Add(link);
}
}
That way you never have to deal with creating the intrim entity yourself.