public async Task <IActionResult> Create(GradeDto gradeDto) { if (await _gradeService.GetGradeByNameAsync(gradeDto.GradeName.ToLower()) == false) { await _gradeService.AddAsync(_mapper.Map <Grade>(gradeDto)); ViewBag.ErrorMessage = ""; return(RedirectToAction("GetAll", "Grade")); } ViewBag.ErrorMessage = "Sistemde aynı isme ait sınıf bulunmaktadır...!"; return(View(gradeDto)); }