无法返回null（System.Boolean不能为null）

Question

I want to return int and bool values to WP page from the database using WCF service. When those fields in the database are null I'm getting an exception:

The formatter threw an exception while trying to deserialize the message: There was an error while trying to deserialize parameter http://tempuri.org/:someFuncResult . The InnerException message was 'ValueType 'System.Boolean' cannot be null. Please see InnerException for more details.

With int type I have the same problem.

Piece of my database looks like:

[boolValue]    BIT    NULL,
[intValue]     INT    NULL,

My service implementation:

     public someClass someFunc(int check)
    {
return (from a in datacontext.someTable
                where a.number == check
                select new someClass ()
                {
                    intValue2 = (int?)a.intValue ,
                    boolValue2 = (bool?)a.boolValue,                
                }).Single();
    }

My service interface:

    [OperationContract]
   someClass someFunc(int check);

    [DataContract]
        public class someClass 
        {
            [DataMember]
            public int? intValue2 { get; set; }
            [DataMember]
            public bool? boolValue2 { get; set; }
        }

Answer 1

As Nullable<bool> field was introduced recently, reference on client side for my service wasn't updated. After updating the reference it worked.

Answer 2

the database null is different then standard null

use this function

 static bool ConvertToBool(object Dnull)
        {
            try
            {
                DBNull a = (DBNull)Dnull;
                string u = a.ToString();

                if (u.Length > 0)
                {
                    return false;
                }
                else
                {
                    return true;
                }
            }
            catch (InvalidCastException e)
            {
                return false;
            }

        }

and

bool Isnull = ConvertToBool(_sqldatareader["Name"]);

this work fine for in mysql.