SQL Data Reader - handling Null column values

Question

I\'m using a SQLdatareader to build POCOs from a database. The code works except when it encounters a null value in the database. For example, if the FirstName column in the

Answer 1

IsDbNull(int) is usually much slower than using methods like GetSqlDateTime and then comparing to DBNull.Value. Try these extension methods for SqlDataReader.

public static T Def(this SqlDataReader r, int ord)
{
    var t = r.GetSqlValue(ord);
    if (t == DBNull.Value) return default(T);
    return ((INullable)t).IsNull ? default(T) : (T)t;
}

public static T? Val(this SqlDataReader r, int ord) where T:struct
{
    var t = r.GetSqlValue(ord);
    if (t == DBNull.Value) return null;
    return ((INullable)t).IsNull ? (T?)null : (T)t;
}

public static T Ref(this SqlDataReader r, int ord) where T : class
{
    var t = r.GetSqlValue(ord);
    if (t == DBNull.Value) return null;
    return ((INullable)t).IsNull ? null : (T)t;
}

Use them like this:

var dd = r.Val(ords[4]);
var ii = r.Def(ords[0]);
int nn = r.Def(ords[0]);