Hi Jasper

Yes it's possible to access services in a custom class using DI, but your service wouldn't be static.

Using DI:

(There is some information here that might help: https://our.umbraco.com/documentation/Getting-Started/Code/Umbraco-Services/)

But essentially create your custom helper service class like so:

public class JasperHelperService : IJasperHelperService
{
  private readonly IMemberService _memberService;
        public JasperHelperService(IMediaService memberService)
        {
            _memberService = memberService;

        }
    public string SomeHelperMethod(string userName){

        var member = _memberService.GetByUsername(userName);
        return member.Id;
    }
}

You'll need to define an interface for your service

public interface IJasperHelperService
{
    public string SomeHelperMethod(string userName);
}

Then register your custom service with an IUserComposer

    public class RegisterJasperHelperServiceComposer : IUserComposer
    {
        public void Compose(Composition composition)
        {
//Lifetime.Request if it depends on the current request, eg depends context of current member or current published content item, or use Lifetime.Singleton if it's the same context across every request
            composition.Register<IJasperHelperService, JasperHelperService>(Lifetime.Request);
         }
    }

Now in your controllers you can access your HelperService like so

public class BlogPostController : Umbraco.Web.Mvc.RenderMvcController
{
        private readonly IJasperHelperService _jasperHelperService;

        public BlogPostController(IJasperHelperService jasperHelperService)
        {
            _jasperHelperService= jasperHelperService;
        }
        public override ActionResult Index(ContentModel model)
        {
        var memberSomething = _jasperHelperService.SomeHelperMethod("jasper");

    }
}

You could access the JasperHelperService in a view by

IJasperHelperService jasperHelperService = Current.Factory.GetInstance<IJasperHelperService>()

regards

Marc