using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

public class Program

{

    static void Main()

    {

        var fields = new List<IViewModel> {

            { new StringInputViewModel { Name = "StringField", Value = "One" } }, 

            { new NumberInputViewModel { Name = "NumberField", Value = 2 } },

            { new NameInputViewModel { Name = "NameField", Value = "Three" } },

            { new HiddenViewModel { Name = "HiddenField", Value = "We should not see this!" } },

            { new ListInputViewModel { Name = "ListField", Value = new List<string> { "1", "2", "3" } } } 

        };

        PrintNamesAndValues(fields);

    }

    static void PrintNamesAndValues(IEnumerable<IViewModel> viewModels)

    {

        // The first "where" clause will only include view models where one of the classes in the inheritence chain

        // is the "InputViewModel" open generic type. For example, it will include "NameInputViewModel" because it 

        // inherits from "StringInputViewModel" which inherits from "InputViewModel<>". However, it will not include

        // "HiddenViewModel" because none of its base types are "InputViewModel<>".

        var nameAndValuePairs = viewModels

            .Where(DoesViewModelInheritInputViewModel)

            .Select(GetNameAndValue)

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

​

        foreach (var nameAndValue in nameAndValuePairs)

        {

            Console.WriteLine($"{nameAndValue?.Item1} = {nameAndValue?.Item2}");

        }

    }

​

    static Tuple<string, string> GetNameAndValue(IViewModel viewModel)

    {

        var type = viewModel.GetType();

        var name = type.GetProperty("Name")?.GetValue(viewModel);

        var value = type.GetProperty("Value")?.GetValue(viewModel);

​

        if (name == null || value == null)

        {

            return null;

        }

​

        var valueString = (value.GetType().GetInterface(nameof(ICollection)) != null)

            ? string.Join(",", ((IEnumerable<object>)value).Select(x => x.ToString()))

            : value.ToString();

        return new Tuple<string, string>(name.ToString(), valueString);

    }

    static bool DoesViewModelInheritInputViewModel(IViewModel viewModel)

    {

        var type = viewModel.GetType();

        while (type != null)

        {

            if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(InputViewModel<>))

            {

                return true;

            }

​

            type = type.BaseType;

        }

​

        return false;

    }

}

​

public interface IViewModel

{

}

public class FieldViewModel : IViewModel

{

    public string Name { get; set; }

}

​

public class HiddenViewModel : FieldViewModel

{

    public string Value { get; set; }

}

​

public class InputViewModel<TModel> : FieldViewModel

{

    public TModel Value { get; set; }

}

​

public class StringInputViewModel : InputViewModel<string>

{

}

​

public class NumberInputViewModel : InputViewModel<int>

{

}

​

public class NameInputViewModel : StringInputViewModel

{

}

​

public class ListInputViewModel : InputViewModel<List<string>>

{

}

​

​

​