public async Task <IActionResult> AddPaperType(PaperTypeViewModel model)
        {
            if (!ModelState.IsValid)
            {
                return(View(model));
            }

            await this.materials.AddPaperTypeAsync(
                model.Name,
                model.Grammage,
                model.IsActive);

            return(RedirectToAction(nameof(AllPaperTypes)));
        }
        public async Task <IActionResult> EditPaperType(int id, PaperTypeViewModel model)
        {
            if (!ModelState.IsValid)
            {
                return(View(model));
            }

            var success = await this.materials.EditPaperTypeAsync(
                id,
                model.Name,
                model.Grammage,
                model.IsActive);

            if (!success)
            {
                return(NotFound());
            }

            return(RedirectToAction(nameof(AllPaperTypes)));
        }