How to get a Powershell script to launch from Visual Studio

I have a PS script (myscript.ps1) that runs fine when launched from the PS command line. However, when I launch it from a Visual Studio app using the following code, the PS blue screen flashes quickly but nothing else happens (the expectation is the creation of a file). There doesn't appear to be any errors but I suspect one is listed in PS's blue screen.

Btw, launching PS scripts from VS is new to me, although I have set PS's rights and it's trusted folders already.

Process.Start("powershell", "-noexit -file 'c:\Temp\myScript.ps1'")

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David L. HansenCEOAsked:
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Chris DentPowerShell DeveloperCommented:
Depending on your goals there's another way to go about this.

A mini-class with a PS wrapper :)
Add-Type -TypeDefinition @"
using System.Management.Automation;
using System.Management.Automation.Runspaces;

public class PS
{
    PowerShell host = PowerShell.Create(InitialSessionState.CreateDefault());

    public object RunScript(string path)
    {
        return host.AddScript(path).Invoke();
    }
}
"@ -ReferencedAssemblies ([PowerShell].Assembly.Location)

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Once it's created, the method can be invoked after you instantiate the class.
[PS]::new().RunScript('C:\Development\scratch\test.ps1')

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The advantage of this approach is that you can get detailed error information. Runtime errors (terminating errors) will throw as exceptions when Invoke is called. Non-terminating errors are written to host.Streams.Error.
Chris DentPowerShell DeveloperCommented:
I just noticed the VB .NET tag. Is the C# example easy enough for you to translate? I can change it, but I always have to double check VB .NET syntax which is only worthwhile if you find it to be.
David L. HansenCEOAuthor Commented:
No Chris, C# is fine. I'll give it a shot and see how it goes.

ps. I have a simple text log file created which I'd like to be filled with any errors. Can I pass the errors listed in the host.Streams.Error object to that log file easily (If it's not too much trouble...I can open another question for that if you need)?
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David Johnson, CD, MVPRetiredCommented: 
Process.Start("powershell", "-noexit  -ExecutionPolicy Bypass -file 'c:\Temp\myScript.ps1'")

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Chris DentPowerShell DeveloperCommented:
Yes, you can. The Error collection contains a list of ErrorRecord objects. This example should push that to the console, it shows how I would distinguish between the different types of error (runtime vs managed).
Add-Type -TypeDefinition @"
Imports System
Imports System.Management.Automation
Imports System.Management.Automation.Runspaces

Public Class PS
    Dim host As PowerShell = PowerShell.Create(InitialSessionState.CreateDefault())

    Public Function RunScript(path As String) As object
        Try
            Dim value As Object = host.AddScript(path).Invoke()
            If host.HadErrors Then
                For Each errorRecord as ErrorRecord in host.Streams.Error
                    Console.WriteLine(errorRecord.Exception.Message)
                Next
            Else
                Return value
            End If
        Catch e As Exception
            Console.WriteLine(e.Message)
        End Try

        Return Nothing
    End Function
End Class
"@ -ReferencedAssemblies ([PowerShell].Assembly.Location) -Language VisualBasic

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David L. HansenCEOAuthor Commented:
David,

Your "Process.Start" approach results in the same blue screen flash as before and no file creation. I'll keep watching for more suggestions from you while I test Chris's code.
David L. HansenCEOAuthor Commented:
Chris,

The "Host" object that we're instantiating has no "Create" method attached to it (at least not in the namespace I'm seeing). It does however, have a CreateNestedPowerShell method instead. If I use that one instead, I do find the "AddScript" method but  no "HadErrors" property.

I'm using/importing all three namespaces you have in your example. I'm also running VS2015.
Thoughts?
Chris DentPowerShell DeveloperCommented:
It's a static method on the System.Management.Automation.PowerShell class. Be a touch careful about assembly versions though, Visual Studio is terrible at picking a modern version when selecting references. I normally feed it the path revealed by the snippet below when adding the reference:
[PowerShell].Assembly.Location

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That gets it the assembly associated with PowerShell 5.1 not PowerShell 2.0.
David L. HansenCEOAuthor Commented:
Working on that now....
Fernando SotoRetiredCommented:
Have a look at this web page. Calling a PowerShell Script From Your .NET Code.
David L. HansenCEOAuthor Commented:
Chris,

Like you say, I think if we can persuade VS to take a different PowerShell version, we'd be home free.
This code however:
"Add-Type -TypeDefinition @" and "@ -ReferencedAssemblies ([PowerShell].Assembly.Location) -Language VisualBasic"

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surrounding the class code causes the entire class code to display as quoted-text and red-marks the whole thing with a "Statement cannot appear outside of a method body" error.

I'm putting this in an existing VB project so the VB format would be preferable, but whether in C# or VB, can you show me a working example of the ReferencedAssemblies approach please? I don't mind rewriting it to fit my environment/local-paths, etc.

Thanks in advance!
Chris DentPowerShell DeveloperCommented:
Apologies, for your VB project drop all of the Add-Type pieces, they were only so I could past the class into the PS console.

So this goes in as source code:
Imports System
Imports System.Management.Automation
Imports System.Management.Automation.Runspaces

Public Class PS
    Dim host As PowerShell = PowerShell.Create(InitialSessionState.CreateDefault())

    Public Function RunScript(path As String) As object
        Try
            Dim value As Object = host.AddScript(path).Invoke()
            If host.HadErrors Then
                For Each errorRecord as ErrorRecord in host.Streams.Error
                    Console.WriteLine(errorRecord.Exception.Message)
                Next
            Else
                Return value
            End If
        Catch e As Exception
            Console.WriteLine(e.Message)
        End Try

        Return Nothing
    End Function
End Class

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And the referenced assemblies goes in...

1. Open PS and run: [PowerShell].Assembly.Location and copy the path ([PowerShell].Assembly.Location | clip)
2. In Visual Studio
3. Select the project
4. References
5. Add Reference...
6. Browse (button, bottom right)
7. Paste the path from 1 and press Add

At this point you should have a much more up to date assembly loaded, and hopefully it'll support some of the methods we've been using.

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David L. HansenCEOAuthor Commented:
This is the resulting path given by PS:

"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Management.Automation\v4.0_3.0.0.0__31bf3856ad364e35\System.Management
.Automation.dll"

Yesterday actually, I included that particular reference in the project, which was when I got the strange "CreateNestedPowerShell" method instead of the simpler "Create". Luckily, it does appear that I can download any version of the various PS namespaces through NuGet though, but I'm not sure which I need.

Here are the options:
https://www.nuget.org/profiles/PowerShellTeam
Chris DentPowerShell DeveloperCommented:
Hmm okay, well at least that bit is right.

The CreateNestedPowerShell method is a method on the instantiated host, we don't need that one. To create the host in the first place you want the static method on the PowerShell type.

Where this:
PowerShell.Create(InitialSessionState.CreateDefault())

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Is this static method:

https://msdn.microsoft.com/en-us/library/hh470726(v=vs.85).aspx?cs-save-lang=1&cs-lang=vb#code-snippet-1
David L. HansenCEOAuthor Commented:
Using the url you just posted, I tracked backwards (through the webpage's bread-crumb path) and found no specific version number referenced. Perhaps you can look in your object explorer in VS and see the correct version number that way?
Chris DentPowerShell DeveloperCommented:
This is my assemblies full name:

System.Management.Automation, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35

I think you have the right assembly.

Going back to this:

> The "Host" object that we're instantiating has no "Create" method attached to it

The create method is not on the instantiated "Host" object. It's a static method on the PowerShell type (does not require an instantiated object).

You're right that the instantiated "Host" object does not have such a method. But if you've instantiated it, you're done with that part and it's on to loading a script into the Commands collection (using the AddScript method).
David L. HansenCEOAuthor Commented:
It worked! :)

Yesterday, for whatever reason (operator error I'm sure) this line of code:
Dim host As PowerShell = PowerShell.Create(InitialSessionState.CreateDefault())

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wasn't liked by VS so I changed it to this:
Dim host As PowerShell

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and followed that up with the "Create" static method used in a constructor (Sub New) which it didn't like either (saying that a "declaration is expected").

At any rate, it works!

Thank you, thank you!
Chris DentPowerShell DeveloperCommented:
Yay :) Good work :)
David L. HansenCEOAuthor Commented:
A big thank you to everyone who helped!
Hat-tip to David J. and Fernando.
David L. HansenCEOAuthor Commented:
For any future readers of this thread, I later on needed to get this working across a network which required my changing some things. The scope and ExecutionPolicy needed to be altered and since catching all errors was still important to me (which can't be done through a simple shell process) I posted this additional question which was very useful.
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