gistfile1.txt

using System;
using System.Collections.Concurrent;
using System.Linq;
using System.Reflection;

public class MyEntity
{
    public string Name;
    public string MacAddress;
    public bool IsIncredible;
    public DateTime LastConnection;
    public long Id { get; set; }
    
    public MyEntity(long id, string name, string macAddress, bool isIncredible, DateTime lastConnection)
    {
        Id = id;
        Name = name;
        MacAddress = macAddress;
        IsIncredible = isIncredible;
        LastConnection = lastConnection;
    }    
}

public class Program
{
    public static void Main()
    {
        MyEntity element1 = new MyEntity(10, "ghuilobiukg", "E5:AB:4C:D3:24:68", true, new DateTime());
        MyEntity element2 = new MyEntity(5422, "qsdlkjfhmsssszzzz", "F1:7D:89:3E:AB:87", false, new DateTime());
        
        ConcurrentDictionary<string, MyEntity> myTab = new ConcurrentDictionary<string, MyEntity>();
        myTab.GetOrAdd(element1.Id.ToString(), element1);
        myTab.GetOrAdd(element2.Id.ToString(), element2);

        var element = FindEntity<MyEntity>(myTab, "IsIncredible", true);
    }

    public static T FindEntity<T>(ConcurrentDictionary<string, T> dictionary, 
                                  string fieldName, dynamic value)
        where T : class
    {
        FieldInfo[] fields = typeof(T).GetFields(); // Just to see what you can get
        FieldInfo fieldFound = typeof(T).GetField(fieldName);
        if (fieldFound == null)
        {
            Console.Write("field not found into class\n");
            return null;
        }
        
        return (from Item in dictionary
                where fieldFound.GetValue(Item.Value) == value
                select Item.Value).First();
    }
}