User Identifier Resolution

The UserScopedRepositoryDecorator relies on an IUserAccessor<TKey> service to resolve the current user's identity at runtime:

public interface IUserAccessor<TKey>
{
    TKey? GetUserId();
}

Strategy-Based Resolution

Kista uses a composable strategy pattern for user resolution. Multiple strategies can be chained together, and they are evaluated in registration order — the first strategy that successfully resolves a user ID wins (fallback chain pattern).

Available Strategies

Strategy	Package	Description
StaticUserIdentifierStrategy<TKey>	Kista.Owners	Returns a fixed user ID (ideal for background jobs, system users, disconnected scenarios)
ClaimUserIdentifierStrategy<TKey>	Kista.Owners	Resolves from JWT/auth claims
QueryStringUserIdentifierStrategy<TKey>	Kista.Owners	Resolves from HTTP query string parameters
RouteUserIdentifierStrategy<TKey>	Kista.Owners	Resolves from HTTP route values

Registration Examples

Background job with static user:

builder.Services.AddUserAccessor<string>(b => {
    b.AddStatic("system-worker");
});

HTTP application with fallback chain:

builder.Services.AddHttpUserAccessor<string>(b => {
    b.AddClaim("sub");              // Try JWT "sub" claim first
    b.AddQueryString("user_id");    // Fallback to query string
    b.AddRoute("userId");           // Fallback to route value
});

HTTP with static fallback (anonymous user):

builder.Services.AddHttpUserAccessor<string>(b => {
    b.AddClaim("sub");
    b.AddStatic("anonymous");       // Fallback for unauthenticated requests
});

Chained on RepositoryContextBuilder (requires Kista.Manager.AspNetCore):

builder.Services.AddRepositoryContext()
    .UseEntityFramework<MyDbContext>(...)
    .WithHttpUserAccessor<string>(b => {
        b.AddClaim("sub");
        b.AddStatic("background-user");
    });

Creating Custom Strategies

Implement IUserIdentifierStrategy<TKey> to create your own resolution logic:

public class HeaderUserIdentifierStrategy<TKey> : IUserIdentifierStrategy<TKey>
{
    private readonly string headerName;

    public HeaderUserIdentifierStrategy(string headerName = "X-User-Id")
    {
        this.headerName = headerName;
    }

    public TKey? GetUserId(IServiceProvider? serviceProvider = null)
    {
        if (serviceProvider == null)
            return default;

        var httpContextAccessor = serviceProvider.GetRequiredService<IHttpContextAccessor>();
        var value = httpContextAccessor.HttpContext?.Request.Headers[headerName].FirstOrDefault();

        if (value == null)
            return default;

        return (TKey)Convert.ChangeType(value, typeof(TKey));
    }
}

// Register custom strategy
builder.Services.AddUserAccessor<string>(b => {
    b.Add(new HeaderUserIdentifierStrategy<string>("X-User-Id"));
    b.AddStatic("anonymous");
});