CODEWITHSUNDEEP
c#powershell.net-core.net-standard
Maximilian Burszley
Maximilian Burszley

Reputation: 19654

`PowerShell.Create()` returning null

Added reference: PowerShellStandard.Library

Repro inside a default .net-core project:

// ...

using System.Management.Automation;
using System.Collections.ObjectModel;

// ...

public static void Main(string[] args)
{
    Collection<PSObject> output;
    using (PowerShell ps = PowerShell.Create())
    {
        ps.AddScript("$test = Get-Date; $test");
        output = ps.Invoke();
    }

// ...

I've tried it with or without the using block, but I end up with the same result: the Create method is not creating a PowerShell object, but it's also not throwing an exception.

Is this a common issue with the PowerShell .net-standard library? Is there a workaround or another way to solve my problem?

Additional info, this is also happening with the RunspaceFactory class CreateRunspace method as I was exploring a workaround with managing runspaces myself.

Upvotes: 7

Views: 4186

Answers (3)

Patrick Meinecke
Patrick Meinecke

Reputation: 4173

PowerShellStandard is a reference library, it's intended for projects that will be loaded into the same AppDomain as PowerShell. In those scenarios the required assemblies are already loaded, so it would be a waste to pull down the entire SDK.

In order to host PowerShell (or otherwise use PowerShell API's from outside a PowerShell session) you need to reference the PowerShell SDK (for PowerShell Core) or the GAC assemblies (for Windows PowerShell).

To reference the SDK, you need a nuget.config file in the base directory of your project that adds the PowerShell myget as a source. Here's an example

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <packageSources>
    <clear />
    <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
    <add key="dotnet-core" value="https://www.myget.org/F/dotnet-core/api/v3/index.json" />
    <add key="powershell-core" value="https://powershell.myget.org/F/powershell-core/api/v3/index.json" />
  </packageSources>
</configuration>

And add a reference to the SDK in your csproj

<ItemGroup>
    <PackageReference Include="Microsoft.PowerShell.SDK" Version="7.1.3" />
</ItemGroup>

Update 04/15/2021

You don't need the nuget config anymore, the SDK is now available on nuget.

Upvotes: 7

Roman Kuzmin
Roman Kuzmin

Reputation: 42035

Here is the recently released Microsoft.PowerShell.SDK 6.0.4.

It looks like it is designed for PowerShell hosting and related tasks. At least the question like code worked fine in my .NET Core application. This package reference is enough.

Upvotes: 1

Sani Huttunen
Sani Huttunen

Reputation: 24385

Looking through the source of the PowerShellStandard Library I noticed the following lines:

public static System.Management.Automation.PowerShell Create ( System.Management.Automation.Runspaces.InitialSessionState initialSessionState ) { return default(System.Management.Automation.PowerShell); }
public static System.Management.Automation.PowerShell Create (  ) { return default(System.Management.Automation.PowerShell); }
public static System.Management.Automation.PowerShell Create ( System.Management.Automation.RunspaceMode runspace ) { return default(System.Management.Automation.PowerShell); }

Those will always return the default of the sealed PowerShell class and that will always be null.

This makes it that PowerShell isn't (fully) supported in PowerShellStandard Library 5.1.

Same is for RunspaceFactory.CreateRunspace.

Upvotes: 4

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