Question

I have trouble to convert from decimal to hex.

Here is my code:

select new
{
    MessageID = table1.Field<Int32?>("MessageID"),
    MessageIDHex = (String)table1.Field<Int32>("MessageID").ToString("X")
}

It gives me Error

with DBNUll.Value cant not change to System.In32

So I have tried

MessageIDHex= (String)table1.Field<Int32?>("MessageID").ToString("X")} 

but it gives me another error.

How can I fix it or it does have another way to solve it.

Answer 1

Apparently, MessageID can be DBNull. The simplest solution is to read the value as a nullable int (to prevent the conversion error from occurring). If you use Field with a nullable type, DBNull is automatically converted to null, which can then be coerced to 0 with the ?? operator:

MessageIDHex = (table1.Field<Int32?>("MessageID") ?? 0).ToString("X")

Alternatively, if you prefer, you can have DBNull values in the database result in an empty or a null string for MessageIDHex:

MessageIDHex = table1.IsNull("MessageID") ? "" : table1.Field<Int32>("MessageID").ToString("X")
MessageIDHex = table1.IsNull("MessageID") ? null : table1.Field<Int32>("MessageID").ToString("X")