Current User (Principal)

Axiom provides IPrincipalAccessor for accessing the current ClaimsPrincipal in a way that works across both plain .NET contexts and ASP.NET Core.

Two packages are involved:

dotnet add package Allegory.Axiom.Security.Abstractions
dotnet add package Allegory.Axiom.Security

For ASP.NET Core, add the integration package instead of (or alongside) the base package:

dotnet add package Allegory.Axiom.AspNetCore.Security

IPrincipalAccessor

public interface IPrincipalAccessor : ISingletonService
{
    ClaimsPrincipal? Current { get; }
}

Inject IPrincipalAccessor wherever you need the current principal. Returns null when no principal is set.

public class OrderService(IPrincipalAccessor principal) : IOrderService, ITransientService
{
    public Task<Order> PlaceOrderAsync(Order order)
    {
        var userId = principal.Current?.Identity?.FindNameIdentifier();
        // ...
    }
}

Default Implementation

ClaimsPrincipalAccessor is the default implementation. It reads from ClaimsPrincipal.Current, which reflects Thread.CurrentPrincipal in standard .NET contexts.

It is registered with RegistrationStrategy.TryAdd, so providing your own implementation automatically takes precedence.

ASP.NET Core Integration

Adding the Allegory.Axiom.AspNetCore.Security package is all that is required. It automatically provides an HTTP-aware implementation that reads the principal from IHttpContextAccessor.HttpContext.User, falling back to ClaimsPrincipal.Current when no HTTP context is available (for example, in background jobs).

Custom Accessor

Implement IPrincipalAccessor directly for custom scenarios such as test doubles, multi-tenant contexts, or pulling the principal from a custom ambient store.

public class MyCustomPrincipalAccessor : IPrincipalAccessor
{
    private readonly IMyContextProvider _context;

    public MyCustomPrincipalAccessor(IMyContextProvider context)
    {
        _context = context;
    }

    public ClaimsPrincipal? Current => _context.CurrentUser;
}

Because ClaimsPrincipalAccessor is registered with TryAdd, any class that implements IPrincipalAccessor and is registered before it (or uses Replace) will win. The simplest approach is to register your implementation with RegistrationStrategy.Replace:

[Dependency(Strategy = RegistrationStrategy.Replace)]
public class MyCustomPrincipalAccessor : IPrincipalAccessor { ... }