Question

I develop a dnn module and use public class classNameInfo: IHydratable (c#)

Can someone explain why this code always return 0 from the db:

System.Nullable<int> _ProductID;
_ProductID = (oReader["ProductID"] == System.DBNull.Value ? null : (int?)oReader["ProductID"]);

while this code returns the correct value?

int? y = (oReader["ProductID"] == System.DBNull.Value ? null : (int?)oReader["ProductID"]);
if (y != null)
{
_ProductID = (int)oReader["ProductID"];
}
else
{
_ProductID = 0;
} 

Answer 1

If you try to convert anything to int?, it will only work if the type of said anything is exactly int. Every other direct conversion will fail. Since the database types are never “exactly int“, that conversion can’t work.

To make the code shorter, you can use the following statement:

_ProductID = oReader["ProductID"] == System.DBNull.Value ? new int?() : (int)oReader["ProductID"];