static private void AllProductsOfUser() { var products = productDAL.GetAll(); foreach (var item in products.Where(x => x.UserId == currentUser.Id)) { Console.WriteLine($"{item.Id} {item.ProductName}"); } Console.WriteLine("\n Select id of product: "); var id = Console.ReadLine(); var product = products.Where(x => x.UserId == currentUser.Id).First(x => x.Id == int.Parse(id)); Console.WriteLine("Enter responce for this product: "); string responce = Console.ReadLine(); if (product.ResponceId != null) { var resp = responceDAL.Add(new ResponceDTO() { Responce = responce, }); var myResponce = responceDAL.GetAll().First(x => x.Responce == resp.Responce); productDAL.AddResponceId(product.Id.ToString(), myResponce.Id.ToString()); } }