HttpContext.User Identity information always return null

Question

I use .net core 3.1.6. There are lots of answer about this and I try all but failed each time. So I create new test MVC project and add authentication.

I try to use a "CurrentUserService" class and get logged user information. However, every each time I get null result.

My startup.cs

public void ConfigureServices(IServiceCollection services) {
    services.AddDbContext<ApplicationDbContext>(options =>
        options.UseSqlServer(
            Configuration.GetConnectionString("DefaultConnection")));
    services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
        .AddEntityFrameworkStores<ApplicationDbContext>();

    services.AddHttpContextAccessor();
    services.AddScoped<ICurrentUserService, CurrentUserService>();

    services.AddControllersWithViews();
    services.AddRazorPages();


}

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env) {
    if (env.IsDevelopment()) {
        app.UseDeveloperExceptionPage();
        app.UseDatabaseErrorPage();
    }
    else {
        app.UseExceptionHandler("/Home/Error");
        // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
        app.UseHsts();
    }
    app.UseHttpsRedirection();
    app.UseStaticFiles();

    app.UseRouting();

    app.UseAuthentication();
    app.UseAuthorization();

    app.UseEndpoints(endpoints => {
        endpoints.MapControllerRoute(
            name: "default",
            pattern: "{controller=Home}/{action=Index}/{id?}");
        endpoints.MapRazorPages();
    });
}

And my CurrentUserService.cs

public class CurrentUserService : ICurrentUserService {
    private IHttpContextAccessor _httpContextAccessor;
    public CurrentUserService(IHttpContextAccessor httpContextAccessor) {
        _httpContextAccessor = httpContextAccessor;
    //I add x for test purpose and there is no user information here.
        var x = _httpContextAccessor.HttpContext?.User?.FindFirstValue(ClaimTypes.NameIdentifier);
    }

    public string UserId {
        get {
            var userIdClaim = _httpContextAccessor.HttpContext?.User?.FindFirstValue(ClaimTypes.NameIdentifier);
            return userIdClaim;
        }
    }

    public bool IsAuthenticated => UserId != null;
}

ICurrentUser.cs

public interface ICurrentUserService {
        string UserId { get; }
        bool IsAuthenticated { get; }
}

DbContext.cs

public class ApplicationDbContext : IdentityDbContext {
        private readonly ICurrentUserService _currentUserService;

        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
            : base(options) {
        }

        public ApplicationDbContext(
            DbContextOptions<ApplicationDbContext> options,
            ICurrentUserService currentUserService)
            : base(options) {
            _currentUserService = currentUserService;
        }
    }

Debug screenshoot:

Answer 1

HttpContext is only valid during a request.The Configure method in Startup is not a web call and, as such, does not have a HttpContext. When .NET Core creates an ApplicationDbContext class for the call to Configure there is no valid context.

You could get the HttpContext in the controller when you send request Home/Index:

public class HomeController : Controller
{
    private IHttpContextAccessor _httpContextAccessor;

    public HomeController(IHttpContextAccessor httpContextAccessor)
    {
        _httpContextAccessor = httpContextAccessor;
        var x = _httpContextAccessor.HttpContext?.User?.FindFirstValue(ClaimTypes.NameIdentifier); //get in the constructor
    }

    public IActionResult Index()
    {
        // you could also get in your method
        var x = _httpContextAccessor.HttpContext?.User?.FindFirstValue(ClaimTypes.NameIdentifier);
        return View();
    }
}

Result:

Update:

Only if you call this service,then you could get the data:

public class HomeController : Controller
{
    private readonly ICurrentUserService _service;
    public HomeController(ICurrentUserService service)
    {
        _service = service;
    }

    public IActionResult Index()
    {
        var data = _service.UserId;
        return View();
    }
}

If you want to get the data in the middleware,please check:

app.UseRouting();

app.UseAuthentication();
app.UseAuthorization();
app.Use(async (context, next) =>
{
    await next.Invoke();
    var data = context.User.FindFirstValue(ClaimTypes.NameIdentifier);
});

app.UseEndpoints(endpoints =>
{
    endpoints.MapControllerRoute(
        name: "default",
        pattern: "{controller=Home}/{action=Index}/{id?}");
    endpoints.MapRazorPages();
});

Update2:

No matter which way you create the ApplicationDbContext instance,it could not separately get the service unless you call it.Anyway,you always need to call the service in the next business layer.

The simple way is to create a new method then you call ApplicationDbContext:

1.ApplicationContext:

public class ApplicationDbContext : IdentityDbContext
{
    private readonly ICurrentUserService _currentUserService;
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
        : base(options)
    {
    }

    public ApplicationDbContext(
        DbContextOptions<ApplicationDbContext> options,
        ICurrentUserService currentUserService)
        : base(options)
    {
        _currentUserService = currentUserService;

    }
    public string GetId()
    {
        var data = _currentUserService.UserId;
        return data;
    }
}

2.Controller:

public class HomeController : Controller
{
    private readonly ILogger<HomeController> _logger;
    private readonly ApplicationDbContext _context;
    public HomeController(ILogger<HomeController> logger, ApplicationDbContext context)
    {
        _context = context;
        _logger = logger;
    }

    public IActionResult Index()
    {
        var data = _context.GetId();
        return View();
    }
}