public class NavController : Controller
    {
        private IProductRepository repository;
        public NavController(IProductRepository repo)
        {
            repository = repo;
        }
        public PartialViewResult Menu()
        {
            IEnumerable<string> categories = repository.Products.Select(x => x.Category).Distinct().OrderBy(x => x);
            return PartialView(categories);
        }
    }

@model IEnumerable<string>

@{
    Layout = null;
    }
    @Html.ActionLink("Home","List","Product")
    @foreach (var link in Model) { 
    @Html.RouteLink(link.Trim(), new { controller="Product",action="List",category=link.Trim(),page=1})
    }