using System;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        List<Activity> list = new List<Activity>();

        list.Add(new Activity{Id = 1, Name = "xx"});

        list.Add(new Activity{Id = 2, Name = "yy"});

        list.Add(new Activity{Id = 3, Name = "zz"});

        var listAsString = "2,,xx,yy,zz,aa";

        var result = GetObjectListFromDelimitedString<Activity>(list, listAsString, "Name", ",");

        foreach (var item in result)

        {

            Console.WriteLine($"{item.Id} - {item.Name}");

        }

    }

​

    public static string[] GetStringListFromDelimitedString(string delimitedList, string delimiter = ",")

    {

        return delimitedList.Split(new string[]{delimiter}, StringSplitOptions.RemoveEmptyEntries);

    }

​

    public static IEnumerable<T> GetObjectListFromDelimitedString<T>(IEnumerable<T> list, string delimitedList, string propName, string delimiter)

    {

        var splitedList = GetStringListFromDelimitedString(delimitedList, delimiter);

        return splitedList.Select(item =>

        {

            return list.Where(obj =>

            {

                var propValue = obj.GetType().GetProperty(propName).GetValue(obj, null);

                return item.Equals(propValue);

            }

​

            ).Select(obj => (T)Convert.ChangeType(obj, typeof (T))).FirstOrDefault();

        }

​

        ).Where(obj => obj != null);

    }

​

    public class Activity

    {

        public int Id

        {

            get;

            set;

        }

​

        public string Name

        {

            get;

            set;

        }

    }

}