public IActionResult AddCourseStudent([FromBody] List <CourseStudentDto> courseStudentDto) { if (!ModelState.IsValid) { // return 422 return(new Helpers.UnprocessableEntityObjectResult(ModelState)); } try { // save var courseStudentFromRepo = _courseRepository.AddCourseStudent(courseStudentDto); var courseStudentToReturn = _mapper.Map <IEnumerable <CourseStudentDto> >(courseStudentFromRepo); return(Ok(courseStudentToReturn)); } catch (AppException ex) { // return error message if there was an exception return(BadRequest(new { message = ex.Message })); } }