How to retrieve new ID in EF Core using UoW pattern - entity-framework

Question

I'm having trouble retrieving the ID of newly added object in EF Core using the UoW pattern. I have this service:
public class OrderService : IOrderService
{
private IUnitOfWork _uow;
private IOrderRepository _orderRepository;
private IPaymentRepository _paymentRepository;
public OrderService(IUnitOfWork uow,
IOrderRepository orderRepository,
IPaymentRepository paymentRepository)
{
_uow = uow;
_orderRepository = orderRepository;
_paymentRepository = paymentRepository;
}
public int CreateOrder(Logic.Order order)
{
var id = _orderRepository.CreateOrder(order);
var payment = new Data.Payment();
payment.OrderId = id; // at this point, this is -2147353458 something
_paymentRepository.CreatePayment(payment);
// committed at this point but I can't get id unless I re-query
_uow.Commit();
// this is still -2147353458
return id;
}
}
So CreateOrder just adds a new order and then the newly generated ID is returned and used by the Payment object in CreatePayment. The problem with this since after adding, it is not committed yet so EF Core generates a temp id (something like -2147483324) so this is what I get. I then pass this to payment but this part is ok since I think EF is tracking it. The problem is what I return to the UI.
The service is called by the UI and after comitting, I can't get the ID. That's been my problem for hours now.

Answer 1

I've recently came across the same problem as well. Am here just to share my solution for reference.
Rather than to committing the transaction for the Id, you could try utilizing EF relationships.
Ex: the payment and order Model
public class Order
{
public int Id{ get; set; }
public Payment Payment { get; set; }
}
public class Payment
{
public int Id{ get; set; }
public int OrderId{ get; set; }
[ForeignKey("OrderId")]
public Order Order { get; set; }
}
Then in your transaction, you could simply assign the order to payment, EF will automatically insert the created Order Id to payment upon committing the transaction :
public int CreateOrder(Logic.Order order)
{
_orderRepository.CreateOrder(order);
var payment = new Data.Payment();
payment.Order = order;
_paymentRepository.CreatePayment(payment);
_uow.Commit();
return order.id;
}

Answer 2

You need to create an abstract method just like that "void Commit(EntityBase entity)" in your Uow, inside the method call your saveChanges this way you ensure that memory address is the same, so outside of the method you are able to access the property Id, be careful if you're using some Mapper because this may change you Memory Address. Make sure that your are using mapper only after Call UoW.Commit!
public class EntityBase
{
public int Id {get;set}
}
public class AnyOtherEntity : EntityBase
{
}
public void Commit(EntityBase entity)
{
yourContext.SaveChanges(entity);
}
Uow.Commit(AnyOtherEntity);
AnyOtherEntity.Id;

Answer 3

There is no option except commiting the transaction if you want to retrieve the generated unique Id immediately. Also,
// this is still -2147353458
return id;
You can't expect to be changed primitive type after commit. You should get it by order.Id, because after the transaction committed the EF will update entity because EF is tracking the entity.
public int CreateOrder(Logic.Order order)
{
_orderRepository.CreateOrder(order);
// commit the transaction
_uow.Commit();
var payment = new Data.Payment();
// Get the id of inserted row
payment.OrderId = order.Id;
_paymentRepository.CreatePayment(payment);
_uow.Commit();
return order.Id;
}