public void Update()
        {
            Categories.Clear();

            using (ICategoryController controller = factory.CreateCategoryController())
            {
                DataControllerMessage <IEnumerable <CategoryDisplayDTO> > controllerMessage = controller.GetAll();
                if (controllerMessage.IsSuccess)
                {
                    foreach (CategoryDisplayDTO category in controllerMessage.Data)
                    {
                        Categories.Add(category);
                    }
                }
            }
        }