Question

My question is similar to the one here: Select a specific column based on another column's value but in LINQ, using VS2010, C#, .Net 4.0 and LINQ to Entities

Here’s the snippet I’m having an issue with:

var BillingNumbers = (from o in mycontext.MyOrders
                    where o.Status.Description.Trim().ToUpper().Equals("SHIPPED")
                    && (o.ActualShipDate >= date1.Date && o.ActualShipDate < date2.Date)
                    select new
                            {BillingNumber = (
                          o.SiteID == "NYC"? o.NYCBillingNumber.Trim():
                          o.SiteID == "DAL" ? o.DallasBillingNumber.Trim(): "unknown") 
                          });
             foreach (var billingnumber in BillingNumbers)
             {
                sqlcmd = MyDatabase.GetStoredProcCommand("MyBillingNumberSP") as SqlCommand;
                sqlcmd.CommandTimeout = Int32.Parse(Settings.Default.SQL_COMMAND_TIMEOUT.ToString());
                MyDatabase.AddInParameter(sqlcmd, "@BillingNumber", DbType.String, billingnumber);
                MyDatabase.AddOutParameter(sqlcmd, "@MyOutputParam", DbType.Boolean, 1);
                LobjDS = MyDatabase.ExecuteDataSet(sqlcmd);  //GETTING AN ERROR HERE
                bool JobbingApplied = Convert.ToBoolean(MyDatabase.GetParameterValue(sqlcmd, "@MyOutputParam"));
                Console.WriteLine(billingnumber);
             }

The ExecuteDataSet command throws an InvalidCastException with the message:

Failed to convert parameter value from a <>f__AnonymousType0`1 to a String.

What is wrong and why is this anonymous type throwing an error when attempted to interpret it as string?

Answer 1

Replace

MyDatabase.AddInParameter(sqlcmd, "@BillingNumber", DbType.String, billingnumber);

with

MyDatabase.AddInParameter(sqlcmd, "@BillingNumber", DbType.String, billingnumber.BillingNumber);

var billingnumber is a anonymous type with one string property BillingNumber. You need to reference that property, it is not automatically convertible to its first member.

An alternative is to replace

select  new
{   BillingNumber = (
    o.SiteID == "NYC"? o.NYCBillingNumber.Trim():
    o.SiteID == "DAL" ? o.DallasBillingNumber.Trim(): "unknown") 
}

with

select (
    o.SiteID == "NYC"? o.NYCBillingNumber.Trim():
    o.SiteID == "DAL" ? o.DallasBillingNumber.Trim(): "unknown")

Then you don’t need the anonymous type at all.