Select multiple types in the same list...

antonello · **Joined:** Sat Aug 11, 2007 7:55 am **Posts:** 2

Hi guys,

I'm brand new to the forum, since I started using NHibernate yesterday, dropping out the ORM I used to develop for a while (which wasn't bad, but had not the community support (N)Hibernate has).

My question is about the procedure for writing an HBM mapping that makes me select multiple types in the same IList instance of a type, using some polymorphisms.
Something like:

Code:

public class Person {
    public long Id;

    public string FirstName;

    public string LastName;

    public IList Addresses;
}

public class Address {
    public long PersonId;

    public string Street;

    public string Number;

    public string City;

    public string State;

   public string Country;

   public string Zip;
}

public class WorkAddress : Address {
    public string OfficeNumber;
}

The result I would like to obtain is to select from the tables "Address" and "WorkAddress", all the instances related to the "PersonId" field specified.
My assumption was to use several <idbag> (one for each entity type to select) on the same field ("Addresses" in this case).

Could you please correct me if I'm wrong and eventually post me a valid HBM to achieve this result?

Thank you all!
Antonello

xasp · **Posted:** Sun Aug 12, 2007 7:15 am

Hello,

I wonder if it wouldn't be easier to store your address and workaddress records in the same DB table, with one field differenciating both types.
In that case, you only need 1 mapping with a discriminator.

Your mapping will also contain an association 'many-to-one' to the Person class, to allow you to query the address of a given Person.

And/Or your Person class will contain a 'one-to-many' collection to Addresses, which will allow you to execute the inverse operation.

So, you can start by searching in the NHibernate reference documentation for the following keywords: 'discriminator' and 'many-to-one'. This will get you on track.