// POST: api/Users public HttpResponseMessage Post([FromBody] DailyPresence value) { if (ModelState.IsValid) { return((LogicDailyPresence.AddDailyPresence(value)) ? new HttpResponseMessage(HttpStatusCode.Created) : new HttpResponseMessage(HttpStatusCode.BadRequest) { Content = new ObjectContent <String>("Can not add to DB", new JsonMediaTypeFormatter()) }); } ; List <string> ErrorList = new List <string>(); //if the code reached this part - the user is not valid foreach (var item in ModelState.Values) { foreach (var err in item.Errors) { ErrorList.Add(err.ErrorMessage); } } return(new HttpResponseMessage(HttpStatusCode.BadRequest) { Content = new ObjectContent <List <string> >(ErrorList, new JsonMediaTypeFormatter()) }); }