MySQL Bugs: #11542: Call to Stored Procedure throws exception when SP has no arguments

Bug #11542	Call to Stored Procedure throws exception when SP has no arguments
Submitted:	24 Jun 2005 7:37	Modified:	25 Jun 2005 18:40
Reporter:	Steve Terepin	Email Updates:
Status:	Closed	Impact on me:	None
Category:	Connector / NET	Severity:	S2 (Serious)
Version:	1.0.4	OS:	Windows (Win XP SP2)
Assigned to:	Reggie Burnett	CPU Architecture:	Any

Description:
Calls to a Stored Procedure that takes no arguments fail, with an exception that reports "Invalid attempt to access a field before calling Read()".

How to repeat:
      try
      {
        string connectionString = (
          "SERVER=localhost;"
        + "DATABASE=X_SqlTestDatabase_01;"
        + "User ID=root;"
        + "PASSWORD=password"
        ) ;
        using ( System.Data.IDbConnection connection = new MySql.Data.MySqlClient.MySqlConnection(connectionString) )
        {
          connection.Open() ;
          System.Data.IDbCommand command = new MySql.Data.MySqlClient.MySqlCommand() ;
          command.Connection = connection ;
          command.CommandType = System.Data.CommandType.StoredProcedure ;
          command.CommandText = "PurgeAllTables" ;
          command.ExecuteNonQuery() ;
        }
      }
      catch ( System.Exception x )
      {
        string message = x.Message ;
      }

... where the 'PurgeAllTables' stored procedure is defined as follows :

DROP PROCEDURE IF EXISTS `PurgeAllTables` ;
DELIMITER `$`;
CREATE PROCEDURE `PurgeAllTables` ( )
BEGIN
END$
DELIMITER `;`$

Suggested fix:
The problem is in MySql.Data.MySqlClient.StoredProcedure.GetParameterList().

try 
{
  reader = cmd.ExecuteReader();
  reader.Read();                          <= returns false when there are no args
  return reader.GetString(0);
}

Change this to :

try 
{
  reader = cmd.ExecuteReader();
  if ( reader.Read() )
    return reader.GetString(0);
  else
  {
    // The stored procedure defines no arguments
    return null ;
  }
}

Thank you for your bug report. This issue has been committed to our
source repository of that product and will be incorporated into the
next release.

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Additional info:

I wasn't able to reproduce this per se.  It might have been related to another bug report where if you had white space in the parameter list, it would fail.  I applied your suggestion though to return null if .Read() returns false.  I also cleaned up some other related code.

This will be in 1.0.5

Documented in 1.0.5 changelog.