MappingHelper.cs for Type Hierarchies

[dahrnsbrak]

When using type hierarchies in an EF project, the TypeName is not exactly the ElementType.FullName, but rather OfType(ElementType.FullName).
For example:

<EntitySetMapping Name="People">
  <EntityTypeMapping TypeName="IsTypeOf(SchoolModel.Person)">
    <MappingFragment StoreEntitySet="Person">
      <ScalarProperty Name="PersonID" ColumnName="PersonID" />
      <ScalarProperty Name="FirstName" ColumnName="FirstName" />
      <ScalarProperty Name="LastName" ColumnName="LastName" />
    </MappingFragment>
  </EntityTypeMapping>
  <EntityTypeMapping TypeName="IsTypeOf(SchoolModel.Instructor)">
    <MappingFragment StoreEntitySet="Person">
      <ScalarProperty Name="PersonID" ColumnName="PersonID" />
      <ScalarProperty Name="HireDate" ColumnName="HireDate" />
      <Condition ColumnName="HireDate" IsNull="false" />
      <Condition ColumnName="EnrollmentDate" IsNull="true" />
    </MappingFragment>
  </EntityTypeMapping>
  <EntityTypeMapping TypeName="IsTypeOf(SchoolModel.Student)">
    <MappingFragment StoreEntitySet="Person">
      <ScalarProperty Name="PersonID" ColumnName="PersonID" />
      <ScalarProperty Name="EnrollmentDate" 
                      ColumnName="EnrollmentDate" />
      <Condition ColumnName="EnrollmentDate" IsNull="false" />
      <Condition ColumnName="HireDate" IsNull="true" />
    </MappingFragment>
  </EntityTypeMapping>
</EntitySetMapping>

You can see documentation here:
http://msdn.microsoft.com/en-us/library/vstudio/bb399272(v=vs.100).aspx

I've tested this change on my project which uses type hierarchies and it works fine. I did not do any performance checks with the new conditional.

[MikaelEliasson]

Thank you very much! Do you think you can add a test for that?

I have a lot of stuff going on this weekend so I will probably merge this during the next week and publish a new version with this and a few other small fixes.

[dahrnsbrak]

I've made another commit with a test that fails without the fix I previously checked in. I also discovered that the EFQueryHelpers class fails with typed hierarchies. I put in a fix for that which uses reflection - I couldn't find a better way to handle this situation since you need to create the object set of the base type, not the derived type.

[MikaelEliasson]

Looks awesome. I doubt there will be any noticable performance hit as both changes are in parts of the code that shouldn't run many times.

Thank you!