How to pass a parameter from C# to a PowerShell script file?

Question

From the command line I can do.

.\test.ps1 1

How do I pass the parameter when doing this from C#? I've tried

 .AddArgument(1)
 .AddParameter("p", 1)

And I have tried passing values in as IEnumerable<object> in the .Invoke() but $p does not get the value.

namespace ConsoleApplication1
{
 using System;
 using System.Linq;
 using System.Management.Automation;
 class Program
 {
 static void Main()
 {
 // Contents of ps1 file
 // param($p)
 // "Hello World ${p}"
 var script = @".\test.ps1";
 PowerShell
 .Create()
 .AddScript(script)
 .Invoke().ToList()
 .ForEach(Console.WriteLine);
 }
 }
}

• Mike Shepard: This seems to indicate that .AddParameter("p", 1) should work.
• Doug Finke: Yeah, agreed. So far it doesn't pass through to the script.
• Mike Shepard: You've probably found this, where Don Jones uses it and adds a scriptblock parameter
• Doug Finke: Yeah, that's a bit different. If I called test.ps from the cmdline i could do .\test.ps1 (new-object PSObject). I'm trying to figure out how to do that in code.

Answer 1

How's this?

static void Main()
{
 string script = @"C:\test.ps1 -arg 'hello world!'";
 StringBuilder sb = new StringBuilder();
 PowerShell psExec = PowerShell.Create();
 psExec.AddScript(script);
 psExec.AddCommand("out-string");
 Collection<PSObject> results;
 Collection<ErrorRecord> errors;
 results = psExec.Invoke();
 errors = psExec.Streams.Error.ReadAll();
 if (errors.Count > 0)
 {
 foreach (ErrorRecord error in errors)
 {
 sb.AppendLine(error.ToString());
 }
 }
 else
 {
 foreach (PSObject result in results)
 {
 sb.AppendLine(result.ToString());
 }
 }
 Console.WriteLine(sb.ToString());
}

Here's a similar version that passes an instance of a DateTime

static void Main()
{
 StringBuilder sb = new StringBuilder();
 PowerShell psExec = PowerShell.Create();
 psExec.AddCommand(@"C:\Users\d92495j\Desktop\test.ps1");
 psExec.AddArgument(DateTime.Now);
 Collection<PSObject> results;
 Collection<ErrorRecord> errors;
 results = psExec.Invoke();
 errors = psExec.Streams.Error.ReadAll();
 if (errors.Count > 0)
 {
 foreach (ErrorRecord error in errors)
 {
 sb.AppendLine(error.ToString());
 }
 }
 else
 {
 foreach (PSObject result in results)
 {
 sb.AppendLine(result.ToString());
 }
 }
 Console.WriteLine(sb.ToString());
}

• Mike Shepard: I'm not seeing how you passed any parameters to a script.
• Elijah W. Gagne: I understand your question now. I've updated my answer to show a script and passing an argument to it. The easiest way I know to do it is to include the arguments in string you pass psExec.AddScript(script)
• Mike Shepard: Wasn't my question, just something I'm interested in and happened to see your answer after it was posted.
• Doug Finke: That works for strings. What if I want to pass in an instance of class?
• Doug Finke: Yup, the difference is. I was using AddScript. Your example uses AddCommand. This lets AddParameter be used as well.

Answer 2

So, to make a long answer short: Use AddCommand instead of AddScript

Answer 3

another way is to fill the runspace with variables.

 public static string RunPs1File(string filePath, Dictionary<string, object> arguments)
 {
 var result = new StringBuilder();
 using (Runspace space = RunspaceFactory.CreateRunspace())
 {
 space.Open();
 foreach (KeyValuePair<string, object> variable in arguments)
 {
 var key = new string(variable.Key.Where(char.IsLetterOrDigit).ToArray());
 space.SessionStateProxy.SetVariable(key, variable.Value);
 }
 string script = System.IO.File.ReadAllText(filePath);
 using (PowerShell ps1 = PowerShell.Create())
 {
 ps1.Runspace = space;
 ps1.AddScript(script);
 var psOutput = ps1.Invoke();
 var errors = ps1.Streams.Error;
 if (errors.Count > 0)
 {
 var e = errors[0].Exception;
 ps1.Streams.ClearStreams();
 throw e;
 }
 foreach (var line in psOutput)
 {
 if (line != null)
 {
 result.AppendLine(line.ToString());
 }
 }
 }
 }
 return result.ToString();
 }

• user2838376: Actually, the best way to do it!