Further Linq enhancements

Up until now there has been a problem to filter on type in Linq

The problem can be shown with this model:

image

If you want to find SomeSubClass that has a Class2 with a specific name ;

var foo2 = (from v in EcoLinqExtender.PSQuery<Class2>(EcoSpace) 
where (v.Class1.Attribute1 == "5" && v.Name == "5A")
select v.Class1)

But now you also get Class1’s that are not of SomeSubClass. And that is a problem in certain situations.

In Ocl2Ps we would have done:

Class2.allInstances->select(a|((a.Class1.Attribute1 = ‘5’) and (a.Name = ‘5A’))).Class1->FilterOnType(SomeSubClass)

Until now MDriven Linq2Sql logic did not understand the Linq counterpart of FilterOnType – which is OfType<class>(). But now it does:

var foo2 = (from v in EcoLinqExtender.PSQuery<Class2>(EcoSpace) 
where (v.Class1.Attribute1 == "5" && v.Name == "5A")
select v.Class1).OfType<SomeSubClass>()

With this is place the database takes care of all the filtering for us and returns the SomeSubClasses that has any Class2 with the correct criteria.

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