public IActionResult change([FromForm] int id = 0, string Name = null, int IsElective = 0, int Credit = 0) { bool flag = false; this.ViewData["id"] = id; if (Name != null) { flag = courses.Change(id, Name, IsElective, Credit); } else if (id != 0) { this.ViewData["oldInf"] = courses.Search(id).FirstOrDefault(); } this.ViewData["flag"] = flag; return(View()); }