Powershell debugging event -Action code block

Question

I have script watching file creation in a specific directory. I'm using Register-ObjectEvent after creating a System.IO.FileSystemWatcher,

It works great, but if I set a break point in the -Action code block the IDE generates a:

WARNING: Breakpoint Line breakpoint on 'D:\My Stuff\Desktop\scripts\fileWatcher.ps1:15' will not be hit

this message happens right after I drop a file into the directory I'm watching and I can see my Write-Host printing out my message right after the above 'warning'.

Is this normal?
I need to add more code and could really use the debugger.. What can\should I do, so I can debug this code block?

$fsw = [System.IO.FileSystemWatcher] $path

Register-ObjectEvent -InputObject $fsw –EventName Created -SourceIdentifier DDFileCreated -Action { 
    $name = $Event.SourceEventArgs.Name 
    $changeType = $Event.SourceEventArgs.ChangeType 
    $timeStamp = $Event.TimeGenerated 
    Write-Host "The file '$name' was $changeType at $timeStamp" -fore green 
    Out-File -FilePath $logFile -Append -InputObject "The file '$name' was $changeType at $timeStamp"
}

score 4 · Accepted Answer · answered Aug 15 '12 at 19:42

If you trigger the event from a direct powershell command in the same ISE or console session, it actually works:

$path = (Resolve-Path '~\').Path
if(Test-Path "$path\newfile.txt"){ del "$path\newfile.txt" }

$fsw = [System.IO.FileSystemWatcher] $path

Register-ObjectEvent -InputObject $fsw –EventName Created -SourceIdentifier DDFileCreated -Action { 
    $name = $Event.SourceEventArgs.Name  # put breakpoint here, via ISE or script
    $changeType = $Event.SourceEventArgs.ChangeType 
    $timeStamp = $Event.TimeGenerated 
    Write-Host "The file '$name' was $changeType at $timeStamp" -fore green 
}

'foo' | out-file "$path\newfile.txt"   # breakpoint hit

But if you simply hook up the event and wait for some external process to create a file, I see the issue you are hitting.

So if you can add some test code to directly trigger your event, go with that.

If not, read on...

It seems like you cannot enter the debugger while the shell or ISE is waiting for a new command, you can only enter while another command is executing.

Going with that theory, this is the workaround (works for me):

Set your breakpoint
Run your event subscription code
Run the command "Read-Host" in the ISE console window, or from the prompt in the shell
Wait until you know your event should have fired due to external process
Hit "enter" to allow Read-Host to complete

Viola, breakpoint hit!

thanks, at least I now know its not me. I 'debugged it' with the old fashion debugger (boat load of Write-Host). — Pablo, Aug 17 '12 at 00:09
I am having this same problem... and am unable to get debug messages or debugging from my object event. I tried your method, but it does not work ... https://stackoverflow.com/q/70491917 Thoughts? — Jonesome Reinstate Monica, Mar 06 '22 at 04:31

score 0 · Answer 2 · answered Mar 08 '22 at 21:50

0

The real key is to have a loop running so the script never exits. Then debugging and breakpoints work.

E.g.

# At the end of the script.
while ($true) {
    Start-Sleep -Seconds 1
}

More detail is here.

answered Mar 08 '22 at 21:50

Jonesome Reinstate Monica

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Powershell debugging event -Action code block

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