Unexpected NullReferenceException When Using Dependency Injection in ASP.NET Core 7 with Scoped Services
I'm performance testing and I'm reviewing some code and I'm experimenting with I've searched everywhere and can't find a clear answer. I'm encountering a `NullReferenceException` when trying to access a scoped service in my ASP.NET Core 7 application. I'm using a service that depends on `IHttpContextAccessor` to retrieve user context, but it seems to be null when called from a background service. Here's a snippet of my code: ```csharp public class MyBackgroundService : BackgroundService { private readonly IServiceProvider _serviceProvider; public MyBackgroundService(IServiceProvider serviceProvider) { _serviceProvider = serviceProvider; } protected override async Task ExecuteAsync(CancellationToken stoppingToken) { using (var scope = _serviceProvider.CreateScope()) { var myService = scope.ServiceProvider.GetRequiredService<IMyService>(); await myService.DoWorkAsync(); } } } ``` In `IMyService`, I inject `IHttpContextAccessor` like this: ```csharp public class MyService : IMyService { private readonly IHttpContextAccessor _httpContextAccessor; public MyService(IHttpContextAccessor httpContextAccessor) { _httpContextAccessor = httpContextAccessor; } public async Task DoWorkAsync() { var user = _httpContextAccessor.HttpContext?.User; // Further processing... } } ``` When `DoWorkAsync` is called from `MyBackgroundService`, it throws `NullReferenceException` at the line checking `HttpContext`. I tried to debug and noticed that `HttpContext` is indeed null in this context, especially since background services don’t have an HTTP context. I thought about passing necessary data through constructor parameters or using a different approach altogether. However, I want to maintain the best practices for dependency injection and avoid tightly coupling my services. What’s the best way to handle this scenario? Is it common to use `IHttpContextAccessor` in background services, or is there a better pattern to follow here? Any ideas what could be causing this? This is for a REST API running on Ubuntu 22.04. I'm using C# latest in this project. Any ideas how to fix this? I've been using C# for about a year now. I'd really appreciate any guidance on this.