public async Task <IActionResult> OnPost(AddOrUpdateCourseDto AddOrUpdateCourseDto) { if (!TryValidateModel(AddOrUpdateCourseDto)) { return(BadRequest(ModelState)); } var result = await CourseService.AddOrUpdateCourseAsync(AddOrUpdateCourseDto).ConfigureAwait(false); if (!result.Succeeded) { ModelState.AddModelError(string.Empty, result.ErrorMessage); return(BadRequest(ModelState)); } return(Content("/Teacher/Course/CourseList")); }