CODEWITHSUNDEEP
linqgenericsreflection
Yan D
Yan D

Reputation: 402

is there a way to dynamically assign type to a generic linq expression?

is there a way to get an object from a collection of a specific subtype when subtype is only known at run time? something like: 

class A
{}

class B : A
{}

class C : A
{}

Main()
{ 
  List<A> outsideList = new List<A>() {new A(), new B(), new C()};

     foreach(var ojb in outsideList)
     {
       dosomethingwithanobject(ojb);
     }
}

void dosomethingwithanobject(A obj)
{
     List<A> intenalList = new List<A>() { new C(), new A(), new B()};
   // this can be A, B or C
   type DESIREDTYPE = typeof(obj);

  var item = list.GetSubType<DESIREDTYPE>().FirstOrDefault();

      // do something with the item
}

Upvotes: 0

Views: 39

Answers (2)

NetMage
NetMage

Reputation: 26917

LINQ has two operations for transforming a sequence of unknown (or parent) types to subtypes: Cast and OfType.

Cast applies the type conversion to each element and fails if it is invalid. OfType only returns the elements that can be converted to the new type.

So,

var item = list.OfType<DESIREDTYPE>().FirstOrDefault();

Upvotes: 0

kapd
kapd

Reputation: 659

I think you can use the the following code:

var result = intenalList.Where(x => x.GetType() == obj.GetType()).FirstOrDefault();

Upvotes: 1

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