ASP.NET : How to Manage State in Class Library? - asp.net

Question

I have an ASP.NET MVC 6 application with a few class libraries (.NET 4.6.1). Now I want to pass the values between the asp.net application and the class libraries. For example I want to access UserId (that is inside a session) from the class library. I don't want to use parameters to pass the value, because UserId is a global variable in my class library and I don't have a reference from web application in the class library. What is the best way to solve this?
Use Sessions in a class library?
Use Shared Memory ?
Use Web Service ?
Use Dtabase ?
... ?
Update :
https://stackoverflow.com/a/2040623/2455393 says that we can use this :
using System.Web;
var currentSession = HttpContext.Current.Session;
var myValue = currentSession["myKey"];
in .NET 4.6.1 (MVC 6) it does not work. but in .NET 4.0 it works well. this is my problem.

Answer 1

I don't have a reference from web application in the class library.
What is the best way to solve this?
Ideally, class library should never have access to HttpContext (unless it is related to presentation layer). Instead, you just pass UserId as a parameter to methods.
Otherwise, it will be hard to unit test the class library.
How about Presentation Layer
If you want to access userId inside controller, you want to inject it, instead of accessing it from HttpContext directly.
For example,
public interface IUserSession
{
int Id { get; }
string FirstName { get; }
string LastName { get; }
string UserName { get; }
bool IsInRole(string roleName);
}
public interface IWebUserSession : IUserSession
{
Uri RequestUri { get; }
string HttpRequestMethod { get; }
}
public class UserSession : IWebUserSession
{
public int Id => Convert.ToInt32(((ClaimsPrincipal) HttpContext.Current.User)?.FindFirst(ClaimTypes.Sid)?.Value);
public string FirstName => ((ClaimsPrincipal)HttpContext.Current.User)?.FindFirst(ClaimTypes.GivenName)?.Value;
public string LastName => ((ClaimsPrincipal) HttpContext.Current.User)?.FindFirst(ClaimTypes.Surname)?.Value;
public string UserName => ((ClaimsPrincipal)HttpContext.Current.User)?.FindFirst(ClaimTypes.Name)?.Value;
public bool IsInRole(string roleName) => HttpContext.Current.User.IsInRole(roleName);
public Uri RequestUri => HttpContext.Current.Request.Url;
public string HttpRequestMethod => HttpContext.Current.Request.HttpMethod;
}
Usage
public class MyController : Controller
{
private readonly IWebUserSession _webUserSession;
public MyController(IWebUserSession webUserSession)
{
_webUserSession = webUserSession;
}
}