Capturing PowerShell output in C# after execution of each pipeline command

Question

I am implementing a WPF application that executes a PowerShell script for each key/value pair given in a dictionary, using the pair as script arguments. I store each run of the script as a new command in the pipeline. However, this causes me to only get output back from the last command that was run, when I need the output after each run of the script. I have considered creating a new pipeline each time the script is executed, but I need to know when all executions of the script are done. Here's the relevant code to help explain my problem:

private void executePowerShellScript(String scriptText, Dictionary<String, String> args)
{
     // Create the PowerShell object.
     PowerShell powerShell = PowerShell.Create();

     // If arguments were given, add the script and its arguments.
     if (args != null)
     {
          foreach (KeyValuePair<String, String> arg in args)
          {
               powerShell.AddScript(scriptText);
               powerShell.AddArgument(arg.Key);
               powerShell.AddArgument(arg.Value);
          }
     }

     // Otherwise, just add the script.
     else
          powerShell.AddScript(scriptText);

     // Add the event handlers.
     PSDataCollection<PSObject> output = new PSDataCollection<PSObject>();
     output.DataAdded += new EventHandler<DataAddedEventArgs>(Output_DataAdded);
     powerShell.InvocationStateChanged +=
          new EventHandler<PSInvocationStateChangedEventArgs>(Powershell_InvocationStateChanged);

     // Invoke the pipeline asynchronously.
     IAsyncResult asyncResult = powerShell.BeginInvoke<PSObject, PSObject>(null, output);
}

private void Output_DataAdded(object sender, DataAddedEventArgs e)
{
     PSDataCollection<PSObject> myp = (PSDataCollection<PSObject>)sender;

     Collection<PSObject> results = myp.ReadAll();
     foreach (PSObject result in results)
     {
          Console.WriteLine(result.ToString());
     }
}

And then I use the following method to know when all executions of the script have been completed. Since I do this by checking that the invocation state of the pipeline is completed, I can't make a new pipeline for each execution of the script:

private void Powershell_InvocationStateChanged(object sender, PSInvocationStateChangedEventArgs e)
{
     switch (e.InvocationStateInfo.State)
     {
          case PSInvocationState.Completed:
               ActiveCommand.OnCommandSucceeded(new EventArgs());
               break;
          case PSInvocationState.Failed:
               OnErrorOccurred(new ErrorEventArgs((sender as PowerShell).Streams.Error.ReadAll()));
               break;
     }
     Console.WriteLine("PowerShell object state changed: state: {0}\n", e.InvocationStateInfo.State);
}

So, to get to my question:

1) Can I force the pipeline to produce output after each command that it executes? Or,
2) If I were to create a new pipeline each time I run the command, is there another way that I could check that all executions of the script have been completed?

There are few examples using the actual PowerShell class in C# and I know next to nothing about threading, so any help would be greatly appreciated.

kck · Accepted Answer · 2012-06-28 12:28:18Z

4

I feel silly for answering my own question, but all I did was move the loop functionality from my C# code into my script and that worked. So now I pass all the keys and values at once as array parameters and only have the one command in the pipeline.

I would still be interested to know if it is possible to produce output after each command in the pipeline is executed, though.

answered Jun 28, 2012 at 12:28

kck

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Comments

user7238761 · Accepted Answer · 2016-12-01 23:18:45Z

0

I have a situation where I have an object that manages a PowerShell environment, and it takes a script or a module and cmdlet and executes it and then takes a new script or module and cmdlet or cmdlet from the original module and executes it. Each time something is executed, I need to return the results. I solved it by clearing the command queue after each execution:

powerShellInstance.Commands.Clear();

hope this helps.

answered Dec 1, 2016 at 23:18

user7238761

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