How to call an Oracle function with a Ref Cursor as Out-parameter from C#?

Question

I'm using a product that provides a database API based on Oracle functions and I'm able to call functions via ODP.NET in general. However, I can't figure out, how to call a function that includes a Ref Cursor as Out-parameter. All the samples I found so far either call a procedure with Out-parameter or a function with the Ref Cursor as return value. I tried to define the parameters similiarly, but keep getting the error that the wrong number or type of parameters is supplied.

Here is the function header (obviously obfuscated):

FUNCTION GetXYZ(
   uniqueId       IN   somepackage.Number_Type,
   resultItems    OUT  somepackage.Ref_Type)
   RETURN somepackage.Error_Type;

These are the type definitions in "somepackage":

SUBTYPE Number_Type IS NUMBER(13);
TYPE Ref_Type IS REF CURSOR;
SUBTYPE Error_Type IS NUMBER;

And this is the code that I have tried:

string sql = "otherpackage.GetXYZ";
var getXYZCmd = OracleCommand oracleConnection.CreateCommand(sql);
getXYZCmd.CommandType = CommandType.StoredProcedure;

getXYZCmd.Parameters.Add("uniqueId", OracleDbType.Int32).Value = uniqueExplosionId;
getXYZCmd.Parameters.Add("resultItems", OracleDbType.RefCursor).Direction = ParameterDirection.Output;
getXYZCmd.Parameters.Add("return_value", OracleDbType.Int32).Direction = ParameterDirection.ReturnValue;

The I tried the following different ways to call the function (of course only one at a time):

var result = getXYZCmd.ExecuteNonQuery();
var reader = getXYZCmd.ExecuteReader();
var scalarResult = getXYZCmd.ExecuteScalar();

But each of them fails with the error message:

Oracle.DataAccess.Client.OracleException: ORA-06550: line 1, column 15:
PLS-00306: wrong number or types of arguments in call to 'GETXYZ'
ORA-06550: line 1, column 15:
PLS-00306: wrong number or types of arguments in call to 'GETXYZ'
ORA-06550: line 1, column 7:
PL/SQL: Statement ignored.

So is it generally possible to call a function with a Ref Cursor as Out-parameter from C# with ODP.NET? I can call a function with the same structure with a Varchar2-Out-parameter instead of the Ref Cursor without problems...

Btw, I'm using ODP.NET version 2.112.2.0 from C#.NET 3.5 in Visual Studio 2008.

Thanks in advance for your help!

Answer 1

You sure can. There are a few gotchas to be wary of but here is a test case

create or replace function testodpRefCursor(
                  uniqueId    IN NUMBER 
                 ,resultItems OUT NOCOPY SYS_REFCURSOR) RETURN NUMBER
                 IS

 BEGIN
      OPEN resultItems for select level from dual  connect by level < uniqueId ;
      return 1;
 END testodpRefCursor;

1. I have found that functions likes to have the ReturnValue as THE FIRST param in the collection
2. BindByName is by default FALSE, so it defaults to BIND BY POSITION

Otherwise it is quite straight forward:

  OracleCommand cmd = new OracleCommand("TESTODPREFCURSOR", con);
  cmd.CommandType   = CommandType.StoredProcedure;
  cmd.BindByName = true;
  // Bind 


  OracleParameter oparam = cmd.Parameters.Add("ReturnValue", OracleDbType.Int64);
  oparam.Direction = ParameterDirection.ReturnValue ;       

  OracleParameter oparam0 = cmd.Parameters.Add("uniqueId", OracleDbType.Int64);
  oparam0.Value = 5 ;
  oparam0.Direction = ParameterDirection.Input;

  OracleParameter oparam1 = cmd.Parameters.Add("resultItems", OracleDbType.RefCursor);
  oparam1.Direction = ParameterDirection.Output;




  // Execute command
  OracleDataReader reader;
  try
  {
    reader = cmd.ExecuteReader();

    while(reader.Read() ){
        Console.WriteLine("level: {0}", reader.GetDecimal(0));  
    }

  } ...

Now for more samples go to your Oracle Home directory and look @ the Ref cursor samples in ODP.NET

for instance: %oracle client home%\odp.net\samples\4\RefCursor

hth