Question

I have 3 types of objects, TypeA,TypeB,TypeC. TypeA has a list of TypeB and TypeB has a list of TypeC, and TypeC has some variables I wanna keep track of

Class TypeA
{
  List<TypeB> MyListOfTypeB;
  //...
}

Class TypeB
{
  List<TypeC> MyListOfTypeC;
  //...
}

Class TypeC
{
  int SomeInteger;
  //...
}        

Given a List<TypeA> MyListOfTypeA, I wanna look for all TypeC Objects which fulfill a certain condition, such as, SomeInteger > 100. Other than nesting for/foreach loops, what is the Linq way to do this?

Answer 1

var MyListOfTypeA = new List<TypeA>();
// ...
var cItems = 
    from a in MyListOfTypeA
    from b in a.MyListOfTypeB
    from c in a.MyListOfTypeC
    where c.SomeInteger > 100
    select c;

The above is equivalent to calling the SelectMany LINQ function, but in my opinion it is significantly cleaner and easier to read.

Doing it with LINQ functions (as already suggested by Dmitry, though with some modifications):

var cItems = 
    MyListOfTypeA.SelectMany( a => a.MyListOfTypeB )
                 .SelectMany( b => b.MyListOfTypeC )
                 .Where( c => c.SomeValue > 200 );