MVC Identity 2 using FormsAuthenticationTicket

Question

I am replacing the (HttpContext.Current.User) IPrincipal with a custom version so I can store more information login and the user. I have done this before using the FormsAu

Answer 1

There are Claims that serve exactly the same purpose. Only new API is actually purposed this way.

Claims are a basically a Dictionary that is stored in auth-cookie and available through IPrincipal. But you don't need to do ICustomPrincipal because actual object that you get behind IPrincipal is ClaimsPrincipal and that has a list of claims.

You'd add extra information to Idnentity object just before the login:

public async override Task CreateIdentityAsync(ApplicationUser applicationUser)
{
    var identity = await base.CreateIdentityAsync(applicationUser, DefaultAuthenticationTypes.ApplicationCookie);

    identity.AddClaim(new Claim("MyApp:FullName", applicationUser.FullName));
    return identity;
}

And then you'd be able to get this data out from IPrincipal via extension:

public static String GetFullName(this IPrincipal principal)
{
    var claimsPrincipal = principal as ClaimsPrincipal;
    if (claimsPrincipal == null)
    {
         throw new Exception("User is not logged in!");
    }
    var nameClaim = principal.Claims.FirstOrDefault(c => c.Type == "MyApp:FullName");
    if (nameClaim != null)
    {
        return nameClaim.Value;
    }

    return String.Empty;
}

I have used this method successfully in a few projects already. See other similar answers for more code samples.
Here is another article, though I discourage from using Thread.CurrentPrincipal or ClaimsPrincipal.Current in MVC application - you don't always get what you expect, especially when user is not logged in or on early stages of AppPool start up.