// int CheckNumOpenSeats(Session session)
/// <summary>
/// Get the number of open seats in the given session.
/// </summary>
/// <param name="session">The session you are checking</param>
/// <returns>
/// The number of open seats in the session. If the session's id is invalid, returns 0.
/// </returns>
public int CheckNumOpenSeats(Session session)
{
if (!(CheckExists(session.Id, Table.SESSION) && CheckExists(session.LocId, Table.LOCATION)))
{
return(0);
}
try
{
_connection.Open();
// We need to lock the records we are reading in the event another person tries to register for the same class at the same time.
var chkNumSeatsTransaction = _connection.BeginTransaction(IsolationLevel.ReadCommitted);
try
{
var cmdNumReservations = new MySqlCommand
{
CommandText = Constants.GETTOTALRESERVATIONS,
Connection = _connection,
Transaction = chkNumSeatsTransaction
};
var cmdGetLocCapacity = new MySqlCommand
{
CommandText = Constants.GETLOCCAPACITY,
Connection = _connection,
Transaction = chkNumSeatsTransaction
};
cmdNumReservations.Parameters.AddWithValue(Constants.SESSID, session.Id);
cmdGetLocCapacity.Parameters.AddWithValue(Constants.LOCID, session.LocId);
int numReservations = 0;
int capacity = 0;
using (var capacityReader = cmdGetLocCapacity.ExecuteReader())
{
capacityReader.Read();
if (capacityReader.HasRows)
{
capacity = Convert.ToInt32(capacityReader[0].ToString());
}
}
using (var rsvpReader = cmdNumReservations.ExecuteReader())
{
rsvpReader.Read();
if (rsvpReader.HasRows)
{
numReservations = Convert.ToInt32(rsvpReader[0].ToString());
}
}
chkNumSeatsTransaction.Commit();
_connection.Close();
return(capacity - numReservations);
}
catch (Exception err)
{
try
{
chkNumSeatsTransaction.Rollback();
ErrorLogger.AddError(err);
return(0);
}
catch (Exception rollerr)
{
ErrorLogger.AddError(rollerr);
return(0);
}
}
}
catch (Exception err)
{
ErrorLogger.AddError(err);
if (_connection.State == ConnectionState.Open)
{
_connection.Close();
}
return(0);
}
}
