using System;

using System.Collections.Generic;

using System.Linq;

using Microsoft.Extensions.Primitives;

public class Program

{

    public static void Main()

    {

        CredentialsCache cache = null;

        //// credentials.Add(new Credentials());

        Dictionary<string, StringValues> strings = new ();

        strings.Add("myKey", new StringValues((string)null));

        bool canParse = strings.TryGetValue("myKey", out StringValues myString);

        Console.WriteLine($"myString value ---{myString.Count}---");

        if (!canParse)

        {

            Console.WriteLine("Cannot Parse");

            return;

        }

        /*if(int.Parse(myString.ToString()) > 0)

        {

            Console.WriteLine("Cannot int.TryParse");

        }*/

        if (myString is {})

        {

            Console.WriteLine("I have a non-null value");

            Console.WriteLine($"myString value ---{myString}---");

            if (cache.CredentialsList.Where(x => x.Username == myString.ToString()).FirstOrDefault() == null)

            {

                Console.WriteLine("I have a null value when comparing");

            }

            return;

        }

        Console.WriteLine("I have a null value");

    }

}

​

  public class Credentials

  {

    /// <summary>

    /// The institution number.

    /// </summary>

    public int InstitutionNumber { get; set; }

​

    /// <summary>

    /// The username.

    /// </summary>

    public string Username { get; set; }

​

    /// <summary>

    /// The password.

    /// </summary>

    public string Password { get; set; }

​

    /// <summary>

    /// The time the credentials expire.

    /// </summary>

    public DateTime ValidUntil { get; set; }

  }

​

  public class CredentialsCache

  {

    /// <summary>

    /// The CredentialsCache constructor.

    /// </summary>

    public CredentialsCache()

    {

      this.CredentialsList = new List<Credentials>();

    }

​

    /// <summary>

    /// The list of credentials.

    /// </summary>

    public List<Credentials> CredentialsList { get; set; }

  }