通过引用 PowerShell 中的 cmdlet 传递参数

Question

我正在尝试用 C# 编写一个简单的 PowerShell cmdlet，它接受一个 ArrayList 实例并向其中添加一个项目。我遇到的问题是数组列表的副本被传递给 cmdlet，而不是我期望的实际对象。有没有办法通过引用传递参数？以下代码仅输出 ArrayList $B 的“Count is 0”。

注意：要在 PowerShell 7.1 中运行程序，您需要以 .NET 5 为目标并安装 Microsoft.PowerShell.SDK 和 System.Management.Automation Nuget 包。

using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Management.Automation;
using System.Management.Automation.Runspaces;

namespace CustomPowerShellCmdlet
{
    class Program
    {
        static void Main(string[] args)
        {
            string powerShellScript = @"

$B  = New-Object System.Collections.ArrayList
Add-CollectionItem -Collection $B -Item '1'
Add-CollectionItem -Collection $B -Item '2'

Write-Output  ('Count is ' + $B.Count)
            ";


            var output = RunPowerShellScript(powerShellScript);

            foreach (PSObject psObject in output)
            {
                Console.WriteLine(psObject.BaseObject.ToString());
            }
        }

        private static Collection<PSObject> RunPowerShellScript(string powerShellScript)
        {
            InitialSessionState initialSessionState = InitialSessionState.CreateDefault();
            initialSessionState.Commands.Add(new SessionStateCmdletEntry("Add-CollectionItem", typeof(AddCollectionItemCmdlet), null));

            using (var runspace = RunspaceFactory.CreateRunspace(initialSessionState))
            {
                runspace.Open();

                using (var ps = PowerShell.Create())
                {
                    ps.Streams.Error.DataAdding += Output_DataAdding;
                    ps.Streams.Debug.DataAdding += Output_DataAdding;
                    ps.Runspace = runspace;

                    ps.AddScript(powerShellScript);

                    return ps.Invoke();
                }
            }
        }

        private static void Output_DataAdding(object sender, DataAddingEventArgs e)
        {
            Console.WriteLine(e.ItemAdded.ToString());
        }

        [Cmdlet(VerbsCommon.Add, "CollectionItem")]
        public class AddCollectionItemCmdlet : Cmdlet
        {
            [Parameter(Mandatory = true)]
            [AllowEmptyCollection]
            public ArrayList Collection { get; set; }

            [Parameter(Mandatory = true)]
            public object Item { get; set; }

            /// <summary>
            /// This static field is needed for demo purposes only.
            /// </summary>
            public static List<object> AddedItems = new List<object>();

            protected override void BeginProcessing()
            {
                Console.WriteLine("A new collection is passed to the cmdlet: {0}", !AddedItems.Any(x => ReferenceEquals(x, Collection)));
                AddedItems.Add(Collection);

                Collection.Add(Item);
            }
        }
    }
}

UPD1. 看来此行为是由 New-Object cmdlet 引起的。如果我用 [System.Collections.ArrayList] @() 替换它，那么我得到了我需要的东西。我仍然不明白为什么它会这样工作。

Answer 1

对象被传递给 cmdlet，但它没有被返回，即 set 被调用，但 get 未被调用。您需要通过管道返回集合并将其重新分配给原始变量。这是工作代码：

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

namespace CustomPowerShellCmdlet
{
    class Program
    {
        static void Main(string[] args)
        {
            string powerShellScript = @"
Write-Output ('PowerShell Version is ' + $PSVersionTable.PSVersion)

$A  = New-Object System.Collections.ArrayList
$A.Add('3') | Out-Null
Write-Output  ('Count is ' + $A.Count)

$B  = New-Object System.Collections.ArrayList
$B = (Add-CollectionItem -Collection $B -Item '1')
$B = (Add-CollectionItem -Collection $B -Item '2')
foreach ($Item in $B) {
    Write-Output $Item
}
Write-Output  ('Count is ' + $B.Count)
";
            var output = RunPowerShellScript(powerShellScript);

            foreach (PSObject psObject in output)
            {
                Console.WriteLine(psObject.BaseObject.ToString());
            }
        }

        private static Collection<PSObject> RunPowerShellScript(string powerShellScript)
        {
            InitialSessionState initialSessionState = InitialSessionState.CreateDefault();
            initialSessionState.Commands.Add(new SessionStateCmdletEntry("Add-CollectionItem", typeof(AddCollectionItemCmdlet), null));

            using (var runspace = RunspaceFactory.CreateRunspace(initialSessionState))
            {
                runspace.Open();
                using (var ps = PowerShell.Create())
                {
                    ps.Runspace = runspace;
                    ps.AddScript(powerShellScript);
                    return ps.Invoke();
                }
            }
        }

        [Cmdlet(VerbsCommon.Add, "CollectionItem")]
        public class AddCollectionItemCmdlet : Cmdlet
        {
            [Parameter(Mandatory = true)]
            [AllowEmptyCollection]
            public ArrayList Collection
            {
                get; set;
            }

            [Parameter(Mandatory = true)]
            public object Item { get; set; }

            protected override void ProcessRecord()
            {
                Collection.Add(Item);
                WriteObject(Collection);
            }
        }
    }
}

Answer 2

这似乎是 PowerShell 中的一个错误，请参阅 https://github.com/PowerShell/PowerShell/issues/14394