using System;

using System.Dynamic;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

            dynamic person = new ExpandoObject();

            person.PostalAddress = new ExpandoObject();

            person.PostalAddress.FullAddressLine = "Blastraat 133, 1234 AB GRONINGEN";

            person.HomeAddress = new ExpandoObject();

            person.HomeAddress.FullAddressLine = "Blastraat 133, 1234 AB GRONINGEN";

            Console.WriteLine(GetAddressLine(null, person));    

​

            person.PostalAddress = null;

            // this should not result in "no address" but the home address to be returned

            Console.WriteLine(GetAddressLine(null, person));    

    }

    public static string GetAddressLine(dynamic unit, dynamic relatedPerson) 

    {

            string adressLine = string.Empty;

            Regex invalidateAdress = new Regex("^[, ]+$");

​

            if (unit != null)

            {

                adressLine = unit.FullAddressLine ?? unit.AddressLine;

            }

            else if (relatedPerson != null && relatedPerson.PostalAddress != null)

            {

                adressLine = relatedPerson.PostalAddress.FullAddressLine ?? relatedPerson.PostalAddress.AddressLine;

            }

​

            if (relatedPerson != null && invalidateAdress.IsMatch(adressLine) && relatedPerson.HomeAddress != null)

                adressLine = relatedPerson.HomeAddress.FullAddressLine ?? relatedPerson.HomeAddress.AddressLine;

​

            if (string.IsNullOrWhiteSpace(adressLine) || invalidateAdress.IsMatch(adressLine))

                adressLine = "Nee";

            return adressLine;      

    }

}