private void PopulateCategories()
        {
            using (var dataContext = new SampleEntitiesDataContext())
            {
                var categories = dataContext.Categories
                            .Select(c => new CategoryViewModel
                            {
                                CategoryID = c.CategoryID,
                                CategoryName = c.CategoryName
                            })
                            .OrderBy(e => e.CategoryName);

                ViewData["categories"] = categories.ToList();
                ViewData["defaultCategory"] = categories.First();
            }
        }