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Mapping inheritance objects

Ilir Lako

17 Jun, 2010 09:08 PM via web

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I have two tables in the database one called Person and one called Faculty. I also have the corresponding classes in code. Faculty inherits from Person.
In the database the primary key for the Person table is personId. The Faculty table also has a personId field which is a foreign key to the Person table.
I have been able to map the Person classt correctly without the Faculty class and got it to work.

public class PersonMap : IAutoMappingOverride

{
    public void Override(AutoMapping<Person> mapping)
    {
        mapping.Id(x =>x.Id).Column("personId").GeneratedBy.Assigned();
    }
}

When I run the code the SQL that is generated from NHibernate is looking for PersonFK in the Faculty table, which of course is not there.

I am struggling with figuring out how to tell it that Person and Faculty are joined on personId and the name of the field is "personId".

I tried something like this but it did not work.
public class FacultyMap : IAutoMappingOverride

{
    public void Override(AutoMapping<Faculty> mapping)
    {
        mapping.JoinedSubClass<Faculty>("personId");
    }
}

It seems like something simple to do and I am sure there is a way to do it, I just don't know how. Any help is greatly appreciated

1. 2 Posted by Ilir Lako on 02 Jul, 2010 06:46 PM

   

   Anybody who can help with this?

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2. Support Staff 3 Posted by Paul Batum on 05 Jul, 2010 12:12 PM

   

   I forget how this works exactly but I think you are really close. Try:

   public class PersonMap : IAutoMappingOverride<Person>
      {
          public void Override(AutoMapping<Person> mapping)
          {
              mapping.Id(x =>x.Id).Column("personId").GeneratedBy.Assigned();
              mapping.JoinedSubClass<Faculty>("personId");
          }
      }

   Let me know if it doesn't work - I'll sit down and figure it out properly.

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3. 4 Posted by Ilir Lako on 08 Jul, 2010 07:09 PM

   

   Hi Paul,
   I tried your suggestion and it did not work. I am still getting the error "Invalid column name 'PersonFk'." Somehow it is still looking for a PersonFk column and the tables are just set to be related on the personId field.
   I would greatly appreciate it if you could look more into it. I have tried everything that I could think of and could find out by the documentation and I am stuck.

   Thanks
   Ilir

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4. Support Staff 5 Posted by Paul Batum on 11 Jul, 2010 07:44 AM

   

   I think theres a bug here and that the best thing to do at this stage is a
   workaround using a convention:

      public class PersonInheritanceConvention : IJoinedSubclassConvention,
   IJoinedSubclassConventionAcceptance
      {
          public void Accept(IAcceptanceCriteria<IJoinedSubclassInspector>
   criteria)
          {
              criteria.Expect(x => x.EntityType.IsSubclassOf(typeof(Person)));
          }

          public void Apply(IJoinedSubclassInstance instance)
          {
              instance.Key.Column("personId");
          }
      }

   Essentially what we're saying in this convention is that for all the joined
   subclasses of person, their key column is "personId".

   I recognise this is not an ideal solution - sorry I can't give you one right
   now.

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