Cannot Watch Folder using FileSystemWatcher in C#

Question

I am attempting to monitor a folder (and its sub-folders) for changes. However, my handler event is never executed. I am using the following code:

FileSystemWatcher m_Watcher = new FileSystemWatcher();
m_Watcher.Path = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + "/Portal 2 Map Installer/"; 
m_Watcher.Filter = "";
m_Watcher.NotifyFilter = NotifyFilters.LastAccess |
             NotifyFilters.LastWrite |
             NotifyFilters.FileName |
             NotifyFilters.DirectoryName;
m_Watcher.IncludeSubdirectories = true;
m_Watcher.Changed += new FileSystemEventHandler(OnFolderChange);
m_Watcher.EnableRaisingEvents = true;

Help please!

That code looks correct to me. The problem must lie elsewhere. What type of file system are you trying to watch? This doesn't work with FAT32 partitions, for example. — Cody Gray - on strike, May 20 '11 at 10:57
I think I've figured it out! For some reason my Form1_Load event is not triggering, which is where I do all of the initialisation. Now to track down why. — YoshieMaster, May 20 '11 at 11:14
Alright, got it working! Now does anyone know how to stop the events being triggered three times? I get the created event triggered, then two changed events. — YoshieMaster, May 20 '11 at 11:16
@Yoshie: You should set properties like this in the constructor: `public Form1()`, rather than in the `Load` event handler method. — Cody Gray - on strike, May 20 '11 at 11:22
You can't stop the event being triggered several times, so you have to work around that. See http://stackoverflow.com/questions/449993/vb-net-filesystemwatcher-multiple-change-events for some suggestions. — sgmoore, May 20 '11 at 11:48
If you are writing for windows 7 ... there is a similar filesystem event watcher in the win7api codepack you may want to have a look at — MaLio, May 20 '11 at 15:26

score 0 · Answer 1 · answered May 20 '11 at 10:57

0

Create a handler for the on error event and see what it says:

  m_Watcher.Error += new ErrorEventHandler(OnError);

answered May 20 '11 at 10:57

Hogan

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Error 3 The property or indexer 'Portal_2_Level_Installer.Form1.OnError' cannot be used in this context because it lacks the get accessor – YoshieMaster May 20 '11 at 11:01
Error 4 'Portal_2_Level_Installer.Form1.OnError' is a 'property' but is used like a 'method' – YoshieMaster May 20 '11 at 11:02
@YoshieMaster: You need to define your OnError handler first. – Hogan May 20 '11 at 12:08

ChrisF · Answer 2 · 2011-05-20T11:06:05.177

0

There are some notes on the Changed event handler :

The Changed event is raised unexpectedly when a file is renamed, but is not raised when a directory is renamed. To watch for renaming, use the Renamed event.

So it would be prudent to handle the Renamed event as well (at the least).

edited May 20 '11 at 11:06

answered May 20 '11 at 10:58

ChrisF

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The folder or it's contents will never be erased. Files are placed into the folder, acted on, then deleted. – YoshieMaster May 20 '11 at 11:06

Cannot Watch Folder using FileSystemWatcher in C#

2 Answers2