public IActionResult OnPostOk() { if (ModelState.IsValid) { if (Agency.ToursId == null) { Agency.ToursId = new List <string>(); } Agency.Id = ObjectId.GenerateNewId().ToString(); _tourList.SynchronizeAdding(Agency); _agencyList.Add(Agency); return(RedirectToPage("TravelAgencies", new { userId = UserId })); } return(Page()); }