How to get the current logged in user Id in ASP.NET Core

Question

I've done this before with MVC5 using User.Identity.GetUserId() but that doesn't seem to work here. The User.Identity doesnt have the GetUserId() method

I am using Microsoft.AspNet.Identity

Answer 1

Update in ASP.NET Core Version >= 2.0

In the Controller:

public class YourControllerNameController : Controller
{
    private readonly UserManager<ApplicationUser> _userManager;
    
    public YourControllerNameController(UserManager<ApplicationUser> userManager)
    {
        _userManager = userManager;
    }

    public async Task<IActionResult> YourMethodName()
    {
        var userId =  User.FindFirstValue(ClaimTypes.NameIdentifier) // will give the user's userId
        var userName =  User.FindFirstValue(ClaimTypes.Name) // will give the user's userName
        
        // For ASP.NET Core <= 3.1
        ApplicationUser applicationUser = await _userManager.GetUserAsync(User);
        string userEmail = applicationUser?.Email; // will give the user's Email

       // For ASP.NET Core >= 5.0
       var userEmail =  User.FindFirstValue(ClaimTypes.Email) // will give the user's Email
    }
}

In some other class:

public class OtherClass
{
    private readonly IHttpContextAccessor _httpContextAccessor;
    public OtherClass(IHttpContextAccessor httpContextAccessor)
    {
       _httpContextAccessor = httpContextAccessor;
    }

   public void YourMethodName()
   {
      var userId = _httpContextAccessor.HttpContext.User.FindFirstValue(ClaimTypes.NameIdentifier);
   }
}

Then you should register IHttpContextAccessor in the Startup class as follows:

public void ConfigureServices(IServiceCollection services)
{
    services.TryAddSingleton<IHttpContextAccessor, HttpContextAccessor>();

    // Or you can also register as follows

    services.AddHttpContextAccessor();
}

For more readability write extension methods as follows:

public static class ClaimsPrincipalExtensions
{
    public static T GetLoggedInUserId<T>(this ClaimsPrincipal principal)
    {
        if (principal == null)
            throw new ArgumentNullException(nameof(principal));

        var loggedInUserId = principal.FindFirstValue(ClaimTypes.NameIdentifier);

        if (typeof(T) == typeof(string))
        {
            return (T)Convert.ChangeType(loggedInUserId, typeof(T));
        }
        else if (typeof(T) == typeof(int) || typeof(T) == typeof(long))
        {
            return loggedInUserId != null ? (T)Convert.ChangeType(loggedInUserId, typeof(T)) : (T)Convert.ChangeType(0, typeof(T));
        }
        else
        {
            throw new Exception("Invalid type provided");
        }
    }

    public static string GetLoggedInUserName(this ClaimsPrincipal principal)
    {
        if (principal == null)
            throw new ArgumentNullException(nameof(principal));

        return principal.FindFirstValue(ClaimTypes.Name);
    }

    public static string GetLoggedInUserEmail(this ClaimsPrincipal principal)
    {
        if (principal == null)
            throw new ArgumentNullException(nameof(principal));

        return principal.FindFirstValue(ClaimTypes.Email);
    }
}

Then use as follows:

public class YourControllerNameController : Controller
{
    public IActionResult YourMethodName()
    {
        var userId = User.GetLoggedInUserId<string>(); // Specify the type of your UserId;
        var userName = User.GetLoggedInUserName();
        var userEmail = User.GetLoggedInUserEmail();
    }
}

public class OtherClass
{
     private readonly IHttpContextAccessor _httpContextAccessor;
     public OtherClass(IHttpContextAccessor httpContextAccessor)
     {
         _httpContextAccessor = httpContextAccessor;
     }

     public void YourMethodName()
     {
         var userId = _httpContextAccessor.HttpContext.User.GetLoggedInUserId<string>(); // Specify the type of your UserId;
     }
}