public IActionResult GetHorsesByBreed(string HorseBreed) { var model = IHorseService.GetHorsesByBreed(HorseBreed); List <HorseResultJson> res = new List <HorseResultJson>(); foreach (var itm in model) { res.Add(new HorseResultJson { BirthDay = itm.DateOfBirth.ToString(), Breed = itm.HorseBreed.ToString(), Breeder = itm.HorseBreeder.ToString(), Name = itm.HorseName.ToString() }); } JsonSerializerSettings jsSettings = new JsonSerializerSettings(); jsSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore; var converted = JsonConvert.SerializeObject(res, null, jsSettings); return(Content(converted, "application/json")); }