Devart Forums

Posted: **Fri 06 Apr 2012 00:31**

With this code (DotConnect Oracle components):

public List GetApplications(long userABCID) {
       List result = new List();
  try {
    using (OracleCommand command = con.CreateCommand()) {
      command.CommandType = System.Data.CommandType.StoredProcedure;
      command.CommandText = "REPORT.ApplicationPermission.GetApplicationCursor";
      // I tried getting just the Application name this way, too:
      //command.CommandText = "REPORT.ApplicationPermission.ApplicationString";
      command.ParameterCheck = true;
      command.Prepare();
      command.Parameters["iWorkerABCID"].Value = userABCID;

using (OracleDataReader reader = ((OracleCursor)command.Parameters["Result"].OracleValue).GetDataReader()) {
      while (reader.Read()) {
        result.Add(reader.GetString("AppName").ToLower());
      }
    }

...I'm getting "Object reference not set to an instance of an object"

Posted: **Fri 06 Apr 2012 12:13**

bclayshannon wrote:using (OracleDataReader reader = ((OracleCursor)command.Parameters["Result"].OracleValue).GetDataReader())

When you create parameters for your command they are not initialized. You have initialized iWorkerABCID parameter, but not the Result parameter. I do not know how your procedure works, but I assume, that 'Result' is an out parameter. And according to the logic of your code you want to get data from the database. In this case such parameter can be initialized, if you execute command.ExecuteNonQuery() before declaring OracleDataReader.

It is also necessary to add the following code before executing the command:

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command.Parameters["Result"].Direction = ParameterDirection.Output;

Posted: **Fri 06 Apr 2012 16:08**

Isn't this unnecessary if you call

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command.Prepare();

?

Posted: **Mon 09 Apr 2012 10:21**

When you perform command.ParameterCheck = true; - the required parameters will be added and redundant parameters will be deleted after executing

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command.Prepare();
//or
command.ExecuteNonQuery();

command.Prepare(); creates a prepared (or compiled) version of the command on the server, but does not execute it.
For more information, please refer to
http://www.devart.com/dotconnect/oracle ... epare.html
If you want to receive some value in the "Result" parameter then you should execute the following code:

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command.ExecuteNonQuery();

Devart Forums

Why is the OracleDataReader that I'm using null?

Why is the OracleDataReader that I'm using null?

Is declaring "Result" as an Output param really necessary?