Subscribing to powershell progress in c# not working

Question

I'm writing a C# GUI program that uses System.Management.Automation to execute powershell commands on an instance created at runtime, I need it to be a persistent powershell instance so I can send multiple commands and collect the output at runtime. This works as intended but i'm having some issues subscribing to the progress event. It only fires when I input faulty commands and writes that the progress is -1 percent complete.

When I input correct commands it doesn't fire at all. The error and output events work properly so i'm not sure what's going wrong.

I found two others having similar problems but their solutions didn't work for me, I linked them down below. Here's the code i'm using unsucessfully so far.

 public class CodeHandler {
   public static PowerShell psInstance;

   public void init() {
     //Create powershell instance
     psInstance = PowerShell.Create();
   }

   public async Task < string > ExecutePowershellCommand(string script) {
     psInstance.AddScript(script);
     psInstance.AddCommand("Out-String");

     PSDataCollection < PSObject > outputCollection = new PSDataCollection < PSObject > ();
     outputCollection.DataAdded += outputCollection_DataAdded;

     //The Part I Can't Get To Work
     psInstance.Streams.Progress.DataAdded += (sender, eventargs) => {
       PSDataCollection < ProgressRecord > progressRecords = (PSDataCollection < ProgressRecord > ) sender;
       Console.WriteLine("!Progress is {0} percent complete", progressRecords[eventargs.Index].PercentComplete);
     };

     psInstance.Streams.Error.DataAdded += Error_DataAdded;

     IAsyncResult result = psInstance.BeginInvoke < PSObject, PSObject > (null, outputCollection);

     while (!result.IsCompleted) {
       Console.WriteLine("Waiting for pipeline to finish...");
       await Task.Delay(100);
     }

     PSInvocationState state = psInstance.InvocationStateInfo.State;
     Console.WriteLine("Execution has stopped. The pipeline state: " + state);
     if (state != PSInvocationState.Completed)
       return string.Empty;

     StringBuilder stringBuilder = new StringBuilder();
     foreach(PSObject outputItem in outputCollection) {
       stringBuilder.AppendLine(outputItem.BaseObject.ToString());
       Console.WriteLine(outputItem.BaseObject.ToString());
     }

     return stringBuilder.ToString();
   }

 }

References:

Getting Write-Progress -PercentComplete status from within C#

Reading Powershell Progress Bar Output in C#

What? It's posted in the question where there's a comment saying this is what I can't get to work — Baxorr
– Baxorr, Commented Feb 14, 2021 at 21:43
"It only fires when I input faulty commands and writes that the progress is -1 percent complete." - do you have an example of a "faulty command" and a "correct command"? If you try to invoke a command that doesn't emit to the Progress stream, then the behavior you describe is expected — Mathias R. Jessen
– Mathias R. Jessen, Commented Feb 14, 2021 at 22:41

It all makes cents · Accepted Answer · 2021-02-15 00:24:14Z

Add psInstance.EndInvoke(result); as shown below:

                       ...
 IAsyncResult result = psInstance.BeginInvoke < PSObject, PSObject > (null, outputCollection);

 while (!result.IsCompleted) {
   Console.WriteLine("Waiting for pipeline to finish...");
   await Task.Delay(100);
 }

 psInstance.EndInvoke(result);

                       ...

Your script needs to use Write-Progress

Example script

# Use Get-Command to get list of commands and store them in the $cmds variable.
$cmds = Get-Command

# Pipe the events to the ForEach-Object cmdlet.
$cmds  | ForEach-Object -Begin {
    # In the Begin block, use Clear-Host to clear the screen.
    Clear-Host

    # Set the $i counter variable to zero.
    $i = 0

    # Set the $out variable to a empty string.
    $out = ""
} -Process {
    # get name
     # Append to the out variable.
     # $out=$out + $_

     write-output ($_.Name + " " + $_.Version) 

    # Increment the $i counter variable which is used to create the progress bar.
    $i = $i+1

    # Use Write-Progress to output a progress bar.
    # The Activity and Status parameters create the first and second lines of the progress bar heading, respectively.
    Write-Progress -Activity "Searching Commands" -Status "Progress:" -PercentComplete ($i/$cmds.count*100)
} -End {
    # Display using the out variable.
    # $out
}

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