Map inheritance from generic class in Linq To SQL

Question

I'm trying to map my inheritance hierarchy to DB using Linq to SQL: Inheritance is like this, classes are POCO, without any LINQ to SQL attributes:

public interface IStage
{ ... }

public abstract class SimpleStage<T> : IStage where T : Process
{ ... }

public class ConcreteStage : SimpleStage<ConcreteProcess>
{ ... }

Here is the mapping:

<Database Name="NNN" xmlns="http://schemas.microsoft.com/linqtosql/mapping/2007">
  <Table Name="dbo.Stage" Member="Stage">
    <Type Name="BusinessLogic.Domain.IStage">
      <Column Name="ID" Member="ID" DbType="Int NOT NULL IDENTITY" IsPrimaryKey="true" IsDbGenerated="true" AutoSync="OnInsert" />
      <Column Name="StageType" Member="StageType" IsDiscriminator="true" />
      <Type Name="BusinessLogic.Domain.SimpleStage" IsInheritanceDefault="true">
        <Type Name="BusinessLogic.Domain.ConcreteStage" IsInheritanceDefault="true" InheritanceCode="1"/>
      </Type>
    </Type>
  </Table>
</Database>

In the runtime I get error: System.InvalidOperationException was unhandled Message="Mapping Problem: Cannot find runtime type for type mapping 'BusinessLogic.Domain.SimpleStage'."

Neither specifying SimpleStage, nor SimpleStage<T> in mapping file helps - runtime keeps producing different types of errors.

DC is created like this:

StreamReader sr = new StreamReader(@"MappingFile.map");
XmlMappingSource mapping = XmlMappingSource.FromStream(sr.BaseStream);
DataContext dc = new DataContext(@"connection string", mapping);

If Linq to SQL doesn't support this, could you, please, advise some other ORM, which does. Thanks in advance,

Regards!

Ksenia

Ksenia Mukhortova · Accepted Answer · 2009-02-28 15:15:38Z

1

I found the answer myself, after I looked into IL of my generic class. In IL its name looks like SimpleStage`1<...> so the issue with mapping file was fixed when I wrote

<Type Name="BusinessLogic.Domain.SimpleStage`1" ...

answered Feb 28, 2009 at 15:15

Ksenia Mukhortova

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Comments

REA_ANDREW · Accepted Answer · 2009-02-28 10:30:48Z

0

Have you added the reference to the files and also are you importing the references with using statements? OR using the fully qualified class names?

answered Feb 28, 2009 at 10:30

REA_ANDREW

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4 Comments

Ksenia Mukhortova Over a year ago

sorry, I didn't quite understand, what references you talk about? if you mean decorating my classes with LINQ related attributes, then no, I use POCO classes and only provide mapping in XML file

REA_ANDREW Over a year ago

Sorry I mean Project->Add Reference then selecting the assembly for BusinessLogic.Domain.IStage Also are you importing the library like using BusinessLogic.Domain;

Ksenia Mukhortova Over a year ago

oh, of course I add the reference to BL assembly and all necessary usings

Ksenia Mukhortova Over a year ago

BTW, without this inheritance hierarchy mapping of other non-inheritant entities works correctly

Frans Bouma · Accepted Answer · 2009-02-28 11:59:27Z

0

I think it's because of the generic type T in SimpleStage: it can't produce internally a mapping lookup table for SimpleStage as T is generic.

answered Feb 28, 2009 at 11:59

Frans Bouma

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1 Comment

Ksenia Mukhortova Over a year ago

yes, I also think its because of generic. but I was wondering if there is a way to perform mapping somehow, maybe using other ORM

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