HttpContextAccessor.HttpContext.User has sometimes null fields (but itself User is not a null)

Question

I have got problem with one of helpers in my project (ASP.NET Core 7 MVC with standard MS AspNetCore.Identity authentication)

DI contains:

services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();

Helper class:

public HelperClassSample(IHttpContextAccessor httpContextAccessor)
{
    _httpContextAccessor = httpContextAccessor;
}

// ... unrelatable code ...

var x = _httpContextAccessor.HttpContext.User

The problem is, that x is never null, but in some cases does not contain any data in ClaimsPrincipal. If I run the app, log out, then log in, and restart browser - everything is fine, there are proper ClaimsPrincipals in x.

But after another reset/rebuild, problem with empty ClaimsPrincipal occurs. What can be the problem?

I cannot use HttpContext from base .NET controller, since the problem occurs in a class which is not a controller. This class (HelperClassSample) is widely used throughout a lot of layers / projects in this solution

Answer 1

the problem occurs in a class which is not a controller. This class (HelperClassSample) is widely used throughout a lot of layers/projects in this solution

Although this is the reality in that code base, this is typically a bad idea. As the documentation for IHttpContextAccessor states:

It also creates a dependency on "ambient state" which can make testing more difficult.

Not only may it make testing more difficult, but the use of Ambient Context also implies that it becomes difficult to reason about which HTTP request a particular execution thread relates to.

This may particularly be true if the code executes on a background thread.

Most likely, the problem reported in the OP is a symptom that the code executes in a context where no user is logged in.

My best advice is to keep HTTP-specific behaviour in the 'Controller layer', instead of distributing it throughout the code base.