public async Task <IActionResult> IndexCategories(int pageNum = 1)
        {
            var categories = await _categoryService.GetCategories(pageNum);

            IndexViewModel <CategoryViewModel> categoryIndexModel = new IndexViewModel <CategoryViewModel>(pageNum, PageSizes.Categories,
                                                                                                           await _categoryService.GetCountCategories(), categories);

            return(View(categoryIndexModel));
        }