title: Check if user is logged in with Token Based Authentication in ASP.NET Core
body: <p>I managed to implement this token based authentication system in my application, but I have a little question. How can I check if a user is signed it (eg if the there is a valid token in the request) within the method? So with the [Authorize] ?</p>
  
  <p>So I have controller, and in that controller I want to check if the user is signed in. I thought of using this:</p>
  
  <pre><code>if (_signInManager.IsSignedIn(ClaimsPrincipal.Current))
  {
      ...
  }
  </code></pre>
  
  <p>but it does not work since ClaimsPrincipal.Current is always null</p>