PrincipalProvider is a way to pass information about a user to various layers of a project

ReadMe.md

PrincipalProvider is a way to pass information about a user to various layers of a project. In this example, the web project registers a concrete WebPrincipalProvider and provides the user from the http context.

You could create a concrete for use in a job/service to provide a system user for example.

You can inject IPrincipalProvider in a service and then call _principalProvider.ClaimsUser.Claims... or get the UserId.

IPrincipalProvider.cs

using System.Security.Claims;

namespace YourProject.Interfaces
{
    /// <summary>
    /// This interface provides a way to inject the user into the services without
    /// crossing responsibilities. 
    /// </summary>
    /// <example>
    /// var userId = _principalProvider.ClaimsUser.GetUserId();
    /// </example>
    public interface IPrincipalProvider
    {
        ClaimsPrincipal User { get; }
    }
}

Startup.cs

namespace YourProject.Web
{
  public class Startup
  {
      public void ConfigureServices(IServiceCollection services)
      {
        services.AddSingleton<IPrincipalProvider, WebPrincipalProvider>();
      }
  }
}

WebPrincipalProvider.cs

using System.Security.Claims;
using Akron.Business.Interfaces;
using Microsoft.AspNetCore.Http;

namespace YourProject.Web
{
    public class WebPrincipalProvider : IPrincipalProvider
    {
        private readonly IHttpContextAccessor _httpContextAccessor;

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

        public ClaimsPrincipal User => _httpContextAccessor.HttpContext.User;
    }
}