Question

Ok, so here’s an enum, right?

    public enum BrandSafe : short
    {

        Yes = 1,
        No = -1,
        Unknown = 0

    }

Underlying datatype of short, OK, so far so good.

Here is a table:

Now, here is a DTO class:

public class VurlRow
{

    public long VurlRMXID { get; set; }
    public string VurlString { get; set; }
    public Enums.BrandSafe BrandSafe  { get; set; }


}

Finally, here is a linq method:

        List<VurlRow> vurls = (from vurl in m_Context.Vurls
                     select new VurlRow()
                                {
                                    BrandSafe = (Enums.BrandSafe)vurl.BrandSafe,
                                    VurlRMXID = vurl.VurlRMXID,
                                    VurlString = vurl.VurlString

                                }).ToList();

I’ve also tried (Enums.BrandSafe)Enum.ToObject(typeof(Enums.BrandSafe), vurl.BrandSafe) to produce the Enum. When I remove the line BrandSafe = (Enums.BrandSafe)vurl.BrandSafe, the call works, but with the line I get a InvalidCast exception.

“Specified cast is not valid.”

Seems like it should be totally valid to me, but what do I know, not enough about enums and linq apparently, can anyone here help?

Answer 1

BrandSafe is tinyint in the database; tinyint maps to byte, not short. That’s the problem. Make it:

public enum BrandSafe : byte
{
    Yes = 1,
    No = -1, // <====== see below
    Unknown = 0
}

(short would map to smallint)

However!!!! Note that -1 is not really a legal value for either of byte/tinyint – it will be 255 or an OverflowException in .NET (depending on whether it is a checked or unchecked context), and an arithmetic-overflow (error 220) at the database.

I do, however, wonder whether bool? (in C#) and bit null (TSQL) would be a better match.