Load Powershell module via .NET code

Question

I have to call PS commands from a VB.NET program. This works fine if I'm calling standard PS commands, but if I have to call a command that lives in a 3rd party module I can't seem to make it work. At the PS console I can type Import-Module MyModule and then I can call the commands in that module. I tried the following but it doesn't work, I still can't access my command from within the module:

Dim PowerShell As Management.Automation.PowerShell = PowerShell.Create()
Dim PowerShellCommand As New PSCommand()
Dim PowerShellCommandResults As Object

PowerShellCommand.AddScript("Import-Module MyModule")
PowerShellCommand.AddScript("Get-MyCommand | Out-String")
PowerShell.Commands = PowerShellCommand
PowerShellCommandResults = PowerShell.Invoke()

How can I do this with the above code example? I don't want to change everything to the Runspace class unless I have to.

Looks like the answer: stackoverflow.com/questions/6266108/… — Andy Arismendi
– Andy Arismendi, Commented May 18, 2012 at 19:36
That answer uses the Runspace class. I already know I can do it using that class, my goal is to do it without that class. — Jimmy D
– Jimmy D, Commented May 18, 2012 at 19:42
Do you get an error? Are there any results in PowerShellCommandResults? — Richard
– Richard, Commented May 21, 2012 at 17:45
There are no errors (if there were I would have posted them) and PowerShellCommandResults contains nothing. However, again, if I call a standard system command then PowerShellCommandResults contains an array of ps objects. Apparently the call to import-module is not working. But it DOES work at the command line, or if I use the Runspace class in my code. — Jimmy D
– Jimmy D, Commented May 21, 2012 at 18:04

Community · Accepted Answer · 2017-05-23 12:06:58Z

-1

The simple code look like as below and it does work:

Dim command As New PSCommand()
command.AddScript("<Powershell command here>")
Dim powershell As Management.Automation.PowerShell = powershell.Create()
powershell.Commands = command
Dim results = powershell.Invoke()

I have explained the following in other thread which one your can choose: Powershell via VB.NET. Which method and why?

If you provide more about the error info I might can help.

Added more Info with full example:

I have just created a very Simple C# DLL and called it from VB.NET as below:

C# DLL Code: (Consider it a 3rd party module)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Xml.Linq;

namespace CSVtoXML
{
  public class Actions
  {
    public Actions()
    {

    }

    public static string writeHello(string name)
    {
        return "Hello " + name;

    }
 }
}

If you want to test this 3rd party DLL in PS command window just use the following:

PS C:\2012>  [Reflection.Assembly]::LoadFile("C:\2012\CSVtoXML.dll")

GAC    Version        Location
---    -------        --------
False  v2.0.50727     C:\2012\CSVtoXML.dll


PS C:\2012> [CSVtoXML.Actions]::writeHello("Avkash")
 Hello Avkash
PS C:\2012>

Now I am using the same steps by loading 3rd party module in VB.NET application as below:

Module Module1
 Sub Main()
    Dim PowerShell As Management.Automation.PowerShell = PowerShell.Create()
    Dim PowerShellCommand As New PSCommand
    PowerShellCommand.AddScript("[Reflection.Assembly]::LoadFile('C:\2012\CSVtoXML.dll')")
    PowerShellCommand.AddScript("[CSVtoXML.Actions]::writeHello('Avkash')")
    PowerShell.Commands = PowerShellCommand
    Dim results = PowerShell.Invoke()
    MsgBox(results.Item(0).ToString())
 End Sub
End Module

Here is the output in debug window to prove that the code does work as expected:

enter image description here

edited May 23, 2017 at 12:06

CommunityBot

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answered May 20, 2012 at 0:58

AvkashChauhan

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4 Comments

AvkashChauhan Over a year ago

I sure read your question and suggest the above code will work. Unless you tell me what did not work, i cant help. You need to tell me explain the problem with error message to dig further, just saying it "did not work" does not help.. thanks for -ve though. Next

Jimmy D Over a year ago

My question clearly explains that I need to call a function in a 3rd party module by FIRST calling import-module. The example that I give does not work, seemingly because the call to import-module does not work. Showing me how to load a dll and call a function by namespace and classname is hardly what I'm looking for.

AvkashChauhan Over a year ago

Thanks for the explanation. Appreciate it. I will get some time to see why Import-module does not work with VB.net and let u know..

Jimmy D Over a year ago

To be clear... import-module works fine if I use the Runspace class in my code. For educational reasons I don't want to use the Runspace class, I want to understand why my original code above does not work. I suspect it has to do with calling add-script twice before the invoke, but if I do add-script invoke, add-script invoke, that also does not work.

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