nhibernate mapping.JoinedSubClass(keyColumn) does not respect keyColumn

Question

I'm using Fluent-NHibernate and attempting to persist an object hierarchy using the table per subclass method:

public class AbstractProduct
{
    public int ProductId { get; set; }
    public string Name { get; set; }
}

public class SingleProduct : AbstractProduct
{
    public int SingleProductId { get; set; }
    public string SomeField { get; set; }
}

when saving an object

        var singleProduct = new SingleProduct();
        session.SaveOrUpdate(singleProduct);

I get this error:

NHibernate.Exceptions.GenericADOException: could not insert: [FluentNHibernateSubClassTest.SingleProduct#3][SQL: INSERT INTO SingleProductData (Field1, AbstractProduct_id) VALUES (?, ?)] ---> System.Data.SqlClient.SqlException: Invalid column name 'AbstractProduct_id'.

despite having the following overrides:

public class AbstractProductOverrides : IAutoMappingOverride<AbstractProduct>
{
    public void Override(AutoMapping<AbstractProduct> mapping)
    {
        mapping.Id(x => x.ProductId).Column("ProductId");
        //this mapping provided to illustrate the overrides are picked up
        mapping.Table("ProductsData");
        mapping.JoinedSubClass<SingleProduct>("ProductId");//ignored??
    }
}

public class SingleProductOverrides : IAutoMappingOverride<SingleProduct>
{
    public void Override(AutoMapping<SingleProduct> mapping)
    {
        mapping.Id(x => x.SingleProductId);
        mapping.Table("SingleProductData");
        mapping.Map(x => x.SomeField).Column("Field1");
    }
}

It doesn't appear to matter what column name I supply to JoinedSubClass it ignores it and uses AbstractProduct_id instead.

How can I tell nhibernate the key column is ProductId and not AbstractProduct_id?

I have a test project demonstrating the issue available here (you need to create the db)

UPDATE I've got around this by providing the following convention:

public class JoinedSubclassConvention : IJoinedSubclassConvention
{
    public void Apply(IJoinedSubclassInstance instance)
    {
        if (instance.EntityType == typeof(SingleProduct))
            instance.Key.Column(("ProductId"));
    }
}

which works but feels like its the wrong way or a hack.

score 2 · Accepted Answer · answered Jan 26 '12 at 14:09

2

mapping.Id in SingleProductOverrides is flawed. Subclasses don't have their own id, they inherit the Id from their base classes. Even mapping.JoinedSubClass<SingleProduct>("ProductId"); is redundant (probably ignored) if SingleProduct is automapped as well (it is as seen from the Override for it). JoinedSubclassConvention is the right way to do this.

answered Jan 26 '12 at 14:09

Firo

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do you have any reference for this (for further reading) please?. Why is it that in `AbstractProduct` the column override is respected but not in the sub-classes?, Please explain the situation where `JoinedSubclass("keyColumn") is used – wal Jan 26 '12 at 14:17
JoinedSubclass("keyColumn") is used when you excluded the subclass from automapping. – Firo Jan 26 '12 at 15:54
Thanks (again). Could I point you in the direction of http://stackoverflow.com/questions/9108388/mapping-nhibernate-parent-child-relationship-the-other-way-round ? :) – wal Feb 02 '12 at 13:47

nhibernate mapping.JoinedSubClass(keyColumn) does not respect keyColumn

1 Answers1