using System;

using System.Linq;

using System.Collections.Generic;

​

public class docsModel

{

    public string Foo { get; set; }

}

public class DtoModel

{

    public List<docsModel> docs { get; set; }

}

public class RequestModel

{

    public docsModel FirstDoc { get; set; }

    public docsModel SecondDoc { get; set; }

    public docsModel ThirdDoc { get; set; }

}

​

class Test

{

    public void method (RequestModel request)

    {

        var create = new DtoModel

        {

            docs = (new [] 

            { 

                request.FirstDoc, 

                request.SecondDoc, 

                request.ThirdDoc

            })

            .Where( d => d != null)

            .Select( d => runFunction(d))

            .ToList()

        };

        Console.WriteLine("The docs property contains {0} instances", create.docs.Count);

        foreach (var d in create.docs)

        {

            Console.WriteLine(d.Foo);

        }

    }

    public docsModel runFunction(docsModel input)

    {

        var output = new docsModel { Foo = input.Foo + "!" };

        return input;

    }

}

​

public class Program

{

    public static void Main()

    {

        var test = new Test();

        var request = new RequestModel

        {

            FirstDoc = new docsModel { Foo = "Hello"}  ,

            SecondDoc = null,

            ThirdDoc = new docsModel { Foo = "World"}

        };

        test.method(request);

    }

}