AutoMapper with auto-incremented values - asp.net

Question

public class OrderDTO
{
public string ClientName { get; set; }
public ICollection<OrderDetailDTO> Details { get; set; }
}
public class Order
{
public string ClientName { get; set; }
public ICollection<OrderDetail> Details { get; set; }
}
public class OrderDetailDTO
{
public int Quantity { get; set; }
public string ProductName { get; set; }
}
public class OrderDetail
{
public int OrderId { get; set; }
public int Quantity { get; set; }
public string ProductName { get; set; }
}
Let's say there are 4 OrderDetailDTO, I want to have the mapped OrderDetail instances with auto-incremented integer values. What I am doing now is post-process the mapped instance.
var mappedOrder = Mapper.Map<OrderDTO, Order>(orderDto);
var orderId = 1;
foreach (OrderDetail detail in mappedOrder.Details)
{
detail.OrderId = orderId++;
}
How can I configure the mapping options, so that the mapped ICollection<OrderDetail> contains 4 OrderDetail instances with OrderId as 1, 2, 3, 4?

Answer 1

You could configure AutoMapper to do this with AfterMap:
Mapper.CreateMap<OrderDTO, Order>()
.AfterMap((src, dest) =>
{
int orderId = 1;
foreach (OrderDetail detail in dest.Details)
{
detail.OrderId = orderId++;
}
});
I don't think there's really a "cleaner" way to do it using AutoMapper.

Answer 2

I use the following method which is much simpler and can be written in a base class or an extension method. The example here uses Generics but can be easily transformed
protected virtual IEnumerable<T> ConvertCsvLines(IEnumerable<TV> lines)
{
var lineNumber = 0;
return lines.Select(x =>
{
var retVal = Mapper.Map<TV, T>(x);
retVal.LineNumber = lineNumber++;
return retVal;
});
}