public IHttpActionResult Create(ExamResponseModel exam)
        {
            if (!this.ModelState.IsValid)
            {
                return(this.BadRequest(this.ModelState));
            }

            var addedExamId = this.exams.Add(exam.Date, exam.Address, exam.CourseId);

            return(this.Ok(addedExamId));
        }
        public IHttpActionResult Update(int id, ExamResponseModel exam)
        {
            if (!this.ModelState.IsValid)
            {
                return(this.BadRequest(this.ModelState));
            }

            var updatedExamId = this.exams.Update(id, exam.Date, exam.Address, exam.CourseId);

            if (updatedExamId == null)
            {
                return(this.NotFound());
            }

            return(this.Ok(updatedExamId));
        }