Cast error message when discovering ref cursor parameter from stored proced

Question

We are today using Microsoft's Oracle provider with some code from the old Data Application Block (from MSDN) to discover parameters from the stored procedures. This code uses the OracleCommandBuilder.DeriveParameters to get the parameters from the stored procedure and command.Parameters.CopyTo copies the discovered parameters into the command object.
If I test with a simple function returning a ref cursor I get one parameter with type refCursor and ParameterDirection.OutPut. This is working fine as long we where using Microsoft's Oracle provider. But using Oracle ODP .NET I get the following error message on datadapter.Fill (I fill a dataset with the result from the reference cursor)
Unable to cast object of Type 'Oracle.DataAccess.Client.OracleDataReader' to type 'Oracle.DataAccess.Types.OracleRefCursor.
If I create a ref parameter manualy like this:
OracleParameter myrefCursor = new OracleParameter();
myrefCursor .OracleDbType = OracleDbType.RefCursor;
myrefCursor .ParameterName = "myParameterName";
myrefCursor .Direction = ParameterDirection.ReturnValue;
and add it to the command object this is working OK. So it seems to be a problem with discovering ref cursor parameters from the database, other parameter types is OK.. I have compared the properties of my manual ref cursor parameter with the one discovered from the stored procedure, but I cannot see any difference. (I see the Value property has some values for the discovered one, but I have set this to DBNull.Value without any result)
Any ideas why I get this error code? Is there any other code blocks I can use to discover the parameters? We send in params object[] with the different values into the helper class and the value is added to the parameter. (Se I don't need to set the data type etc for each parameter, I just need to have the correct order of the parameters)

Answer 1

For accuracy's sake, just wanted to let everyone know that this is actually a bug. The correct bug number is 8423178.
Christian
Mark_Williams wrote:
Just to follow-up on this issue...
The bug has been closed as "not a bug" as it seems undocumented behavior was relied upon for this to work in earlier releases.
Note from the documentation on DeriveParameters:
"The output values of derived parameters return as .NET Types by default. To obtain output parameters as provider types, the OracleDbType property of the parameter must be set explicitly by the application to override this default behavior. One quick way to do this is to set the OracleDbType to itself for all output parameters that should be returned as provider types." (emphasis added)
The issue, as you might already know, is that there is no corresponding .NET Framework Type for an Oracle Ref Cursor and the type is, therefore, set to Object. So, explicitly setting the type to OracleDbType.RefCursor should work.
Regards,
Mark