Get PowerShell.Invoke() output in C#

Question

I have an application, that allows the user to configure basic WMI settings on a Win 10 IoT machine.

I am currently struggling with reading all WEKF_PredefinedKey settings, that are enabled. I am simply running a skript, that I added as string to the project settings named ReadEnabledKeys:

$CommonParams = @{"namespace"="root\standardcimv2\embedded"}
$CommonParams += $PSBoundParameters

    Set-ExecutionPolicy -ExecutionPolicy RemoteSigned;
     $keys = Get-WMIObject -class WEKF_PredefinedKey @CommonParams
        foreach($k in $keys) 
        {
            if($k.Enabled -eq $false)
            {
             "$k";
            }
        }

My call in C# code looks like this (Note: using System.Management.Automation):

 using (PowerShell PowerShellInstance = PowerShell.Create())
        {
          PowerShellInstance.AddScript(Properties.Settings.Default.ReadEnabledKeys);          
          var result = PowerShellInstance.Invoke();
        } 

My variable result will always stay empty. If I run the skript in Powershell directly, the output is just fine (all shortcuts, that are currently not disabled).

I have something similar programmed with the unified write filter, where I enable and disable it:

$COMPUTER = "localhost"
$NAMESPACE = "root\standardcimv2\embedded"

Set-ExecutionPolicy -ExecutionPolicy RemoteSigned;
$objUWFInstance = Get-WMIObject -namespace $NAMESPACE -class UWF_Filter;
$retval = $objUWFInstance.Enable();
if ($retval.ReturnValue -eq 0) {"Unified Write Filter will be enabled after the next system restart."}
else {"Unknown Error: " + "{0:x0}" -f $retval.ReturnValue}

And the C# call:

 using (PowerShell PowerShellInstance = PowerShell.Create())
        {
          PowerShellInstance.AddScript(Properties.Settings.Default.EnableUWF);

          // [0] = result or error
          var result = PowerShellInstance.Invoke();
          if (result[0].ToString().ToLower().Contains("enabled"))
            MessageBox.Show(result[0].ToString(), "", MessageBoxButton.OK, MessageBoxImage.Information);
          else
            MessageBox.Show("Error when enabling the filter!  " + Environment.NewLine + result[0].ToString(), "",
                            MessageBoxButton.OK, MessageBoxImage.Error);
        }

Here my result variable will be filled with the expected strings.

I have tried Write-Host $k, as I suspected something wrong with the stream, but this was without any success.

The output in Powershell looks like this:

PS C:\Users\Administrator> C:\Users\Administrator\Desktop\Newfolder\Untitled1.ps1
\\DESKTOP-RMGOBMG\root\standardcimv2\embedded:WEKF_PredefinedKey.Id="Alt"\\DESKTOP-RMGOBMG\root\standardcimv2\embedded:WEKF_PredefinedKey.Id="Application"
\\DESKTOP-RMGOBMG\root\standardcimv2\embedded:WEKF_PredefinedKey.Id="Ctrl+Esc"
\\DESKTOP-RMGOBMG\root\standardcimv2\embedded:WEKF_PredefinedKey.Id="Ctrl+F4"
\\DESKTOP-RMGOBMG\root\standardcimv2\embedded:WEKF_PredefinedKey.Id="Ctrl+Tab"
.
.
.

Can anyone tell me, what the problem is?

Answer 1

The problem appears to be with your script. Setting the ExecutionPolicy midstream doesn't do anything and you aren't writing a function so adding $PSBoundParameters also doesn't do anything. Here's an example that should work (I'd specify PS version in the future. I know you're on v5.1/win10 due to keyboard filtering)

$collection = [System.Collections.Generic.List[string]]::new()
foreach ($key in (Get-CimInstance -Namespace 'root\standardcimv2\embedded' -ClassName WEKF_PredefinedKey)) {
    if (-not $key.Enabled) {
        $collection.Add($key.ToString())
    }
}
return $collection

(simplified)

@(Get-CimInstance -Namespace root\standardcimv2\embedded -ClassName WEKF_PredefinedKey).
    Where{-not $_.Enabled}.
    ForEach('ToString')

---

Example:

using (PowerShell ps = PowerShell.Create())
{
    string script = @"Import-Module -Name C:\Windows\system32\WindowsPowerShell\v1.0\Modules\Microsoft.PowerShell.Management\Microsoft.PowerShell.Management.psd1 -ErrorAction Stop; @(Get-WmiObject -Namespace root\standardcimv2\embedded -Class WEKF_PredefinedKey -ErrorAction Stop).Where{-not $_.Enabled}.ForEach('ToString')";
    ps.AddScript(script);
    var result = ps.Invoke();
}