Further Linq enhancements

Until now, it has been problematic to filter on type in Linq.

This model shows the problem:

Linq.png

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 Class1s that are not of SomeSubClass.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 in place, the database takes care of all the filtering for us and returns the SomeSubClasses that have any Class2 with the correct criteria.

This page was edited 108 days ago on 02/10/2024. What links here