Question

Hey Folks.
I have an app that writes to the windows event log.
Now i want the same app to be able to read the event log an process the info that is in there.

I use my own dll to do my reading and writing. The Code for the Reading:

    public static EventLog getEventLog(string Source, string Log)
    {
        using(EventLog ev = new EventLog(Log, System.Environment.MachineName, Source))
        {
            if (ev.Entries.Count <= 0)
            {
                return null;
            }
            else 
            { 
                return ev; 

            }            
        }
    }

Here is the code i use to handle the eventlog

private void ProcessEvents()
    {
        using (EventLog ev = EventComms.EventComms.getEventLog("Application", "Application"))
        {
            for (int i = ev.Entries.Count - 1; i >= ev.Entries.Count; i--)
            {
                EventLogEntry CurrentEntry = ev.Entries[i];
                Console.WriteLine("Event ID : " + CurrentEntry.InstanceId);
                Console.WriteLine("Entry Type : " + CurrentEntry.EntryType.ToString());
                Console.WriteLine("Message :  " + CurrentEntry.Message + "\n");
            }   
        }                
    }

Now when i try and do something with the returned Log i get an (ObjectDisposedException was unhandled Message=Cannot access a disposed object.) exception.
I get the exception when i use ev.Entries.Count

Why do i get the error, and what is the best way to deal with it?

Answer 1

You are disposing the returned EventLog object in the getEventLog method. Remove the using statement. Actually, the getEventLog method can return null which you don’t check for later. I suggest dropping the method all together and using this code instead (where I also changed how you loop):

private void ProcessEvents()
{
  using (EventLog ev = new EventLog("Application", System.Environment.MachineName, "Application"))
  {
    for (int i = ev.Entries.Count - 1; i >= 0; i--)
    {
      EventLogEntry CurrentEntry = ev.Entries[i];
      Console.WriteLine("Event ID : " + CurrentEntry.InstanceId);
      Console.WriteLine("Entry Type : " + CurrentEntry.EntryType.ToString());
      Console.WriteLine("Message :  " + CurrentEntry.Message + "\n");
    }
  }
}