Map table inheritance as a one-to-one relationship with NHibernate

Question

Hi!

I have a database that has a one-to-one relationship modeled between a Person and a Address (that uses person id). However, I cannot find a way to make the map using NHibernate.

My table structure is the following:

PersonTable

PersonId
PersonName
PersonAge

AddressTable

PersonId
CountryName
StreetName
StateName

And I would like to have something like this as the final class:

PersonClass

int Id
string Name
int Age
Address HomeAddress

AddressClass

string Street
string Country
string State
Person Owner

I tried with HasOne relationship but I couldn´t reuse PersonId as Address Identifier.

Thanks!

Edit: I forgot to mention that I´m using FluentNHibernate so both fluent mapping and XML will be fine.

Answer 1

The problem is that your database schema does not represent a "Has One" relationship between Person and Address. It represents a "Has Many" relationship; You may be artificially limiting it to be one address per person, but that doesn't change the fact that the model is multiple addresses per person.

To get a "Has One" relationship, you would put the AddressID on the the PersonTable.

Answer 2

I did it using Id().GeneratedBy.Foreign() in Address class map referencing it to the Person´s ID and it worked.

Thanks!

Answer 3

I would map it as a component of Person. In the person ClassMap add the following:

 Component(x => x.Address, m =>
        {
            m.Map(x => x.Street, "Street");
            m.Map(x => x.State, "State");
            // more here
        });

Cheers