How to call extension method “ElementAt”of List with reflection?

Question

I have problem that after creating object \"oListType01\" of type List < MyClass01 > and after assigning it to the another objet \"oObjectType \" of type \"object\" I ca

Answer 1

If we can safely assume that:

• oObjectType is a IEnumerable of some T

then here's the code to extract the items from it.

Note that I seriously wonder if this is the right way to go about this, but you haven't given us enough information to help you figure out if there's a better way, so all we're left with is just answering the question as asked.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Diagnostics;

namespace ConsoleApplication2
{
    class MyClass01
    {
        public String _ID;

        public override string ToString()
        {
            return _ID;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            MyClass01 oMy1 = new MyClass01();
            oMy1._ID = "1";

            MyClass01 oMy2 = new MyClass01();
            oMy2._ID = "3";

            IList oListType01 = new List();

            oListType01.Add(oMy1);
            oListType01.Add(oMy2);

            object oObjectType = new object();

            oObjectType = oListType01;

            Test(oObjectType);

            Console.In.ReadLine();
        }

        private static void Test(object oObjectType)
        {
            Type tObject = oObjectType.GetType();
            Debug.Assert(tObject.IsGenericType);
            Debug.Assert(tObject.GetGenericArguments().Length == 1);
            Type t = tObject.GetGenericArguments()[0];

            Type tIEnumerable = typeof(IEnumerable<>).MakeGenericType(t);
            Debug.Assert(tIEnumerable.IsAssignableFrom(tObject));

            MethodInfo mElementAt =
                typeof(Enumerable)
                .GetMethod("ElementAt")
                .MakeGenericMethod(t);

            Console.Out.WriteLine("o[0] = " +
                mElementAt.Invoke(null, new Object[] { oObjectType, 0 }));
            Console.Out.WriteLine("o[1] = " +
                mElementAt.Invoke(null, new Object[] { oObjectType, 1 }));
        }
    }
}