public ActionResult <CarInsuranceCreationViewModel> Post([FromBody] RegisterCarInsuranceViewModel model) { if (!ModelState.IsValid) { return(BadRequest(ModelState)); } var id = Guid.NewGuid().ToString(); var customer = customerRepository.GetSingle(c => c.CustomerNumber == model.CustomerNumber); if (customer == null) { return(NotFound()); } var valid = CheckValidity(model.DateActive); var premium = CalculatePremium(); var insurance = new CarInsurance { // Customer = customer, CustomerId = customer.Id, DateOfPurchase = DateTime.Now, Id = id, IsActive = valid, Premium = premium, InsuranceNumber = new Random().Next(0, 100).ToString(), DateActive = DateTime.Now, RegistrationNumber = model.RegistrationNumber }; insuranceRepository.Add(insurance); insuranceRepository.Commit(); var thing = new CarInsuranceCreationViewModel { InsuranceId = id }; return(Ok(thing)); }