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This entry has been published on 2017-03-08 and may be out of date.

Last Updated on 2017-03-08.

[:en]Using Microsoft.AspNetCore.Identity, you might miss a method like GetUserId() which was available for previous .NET frameworks by default.

As a workaround, use this extension method:

using System.Security.Claims;

namespace myproject.Common
    public static class ExtensionMethods
        /// <summary>
        /// User ID
        /// </summary>
        /// <param name="user"></param>
        /// <returns></returns>
        public static string getUserId(this ClaimsPrincipal user)
            if (!user.Identity.IsAuthenticated)
                return null;

            ClaimsPrincipal currentUser = user;
            return currentUser.FindFirst(ClaimTypes.NameIdentifier).Value;



using myproject.Common;


var userId = User.getUserId();