powershell - 管道进入 ScriptBlock

Question

我正在尝试找到一些在 PowerShell 中灵活更改/替换管道元素的方法:

Function Where-DirectlyReportsTo {
    Param (
        [Parameter(
            ValueFromPipeline = $true,
            HelpMessage = "The ADUser object to be tested"
        )]
        [Microsoft.ActiveDirectory.Management.ADUser] $ADUser,
        [Parameter( 
            Mandatory = $true,
            ValueFromPipeline = $false,
            Position = 0
        )]
        [String] $mgrDN
    )
    Process {
        If ($ADUser) {
            If ($ADUser.Manager -eq $mgrDN) { Return $ADUser }
        }
    }
}

$Properties = @("Manager")
$users = Get-ADUser -Filter * -SearchBase $OU -Properties $Properties
[ScriptBlock] $sb = {Where-DirectlyReportsTo "CN=Colonel Foobar,$OU"}
$DNs = $users | $sb | %{$_.DistinguishedName}

我想返回向 Foobar 上校报告的所有用户的 DN，但它给了我错误 Expressions are only allowed as the first element of a pipeline.

这是一个微不足道的例子，但我最终希望能够将管道步骤放入一个循环中并向其传递不同的 ScriptBlocks 以获得不同的用户集，或者使用更复杂的 ScriptBlocks(例如:{ Where-IsEmployee | Where-IsInDepartment "财务"| Where-LikesIceCream}).

我意识到我可能做错了，如果有人指出正确的方向，我将不胜感激。

编辑:为了澄清，这里是我想要完成的粗略概述:

[ScriptBlock[]] $arrBlocks = @( # lots of different cases
)
ForEach ($sb In $arrBlocks) {
    $DNs = $users | $sb | %{$_.DistinguishedName}
    # Then do something with the DNs
}

实际上，这可能涉及哈希表而不是数组，这样我就知道如何处理每组结果。

Answer 1

语法错误很简单:

# Wrong:
$DNs = $users | $sb | %{$_.DistinguishedName}

# Correct; note the call operator in front of $sb:
$DNs = $users | &$sb | %{$_.DistinguishedName}

这仍然让您的管道问题陷入死胡同。你不需要在这里花哨；只需通过管道将 $Input 传递给下一个函数:

[ScriptBlock] $sb = {$Input | Where-DirectlyReportsTo "CN=Colonel Foobar,$OU"}

您不应该让 $sb 本身枚举输入。这是额外的开销，如果您使用 param()，会将脚本 block 提升为一个 cmdlet。你真的不需要那个。

事实上，您可以将整个事情简化为四行，甚至是很长的一行:

$properties = @("Manager")
$managers = @(
    "CN=Colonel Foobar,$OU"
    "CN=Sergeant Foobar,$OU"
    "CN=Random Manager,$OU"
)

$users = Get-ADUser -Filter * -SearchBase $OU -Properties $properties
$DNs = $users | ?{ $managers -contains $_.Manager } | %{ $_.DistinguishedName }

我用这段代码测试过:

$OU = 'OU=test'
$users = @(
    @{
        Manager = "CN=Colonel Foobar,$OU";
        DistinguishedName = "Show me!"
    }
    @{
        Manager = "CN=Anon Y Mous,$OU";
        DistinguishedName = "Don't show me!"
    }
    'rabbit'
    42
    $null
    @{
        DistinguishedName = "Don't show me, either!"
    }
    @{
        Manager = "CN=Random Manager,$OU";
        DistinguishedName = "Show me, too!"
    }
)

$managers = @(
    "CN=Colonel Foobar,$OU"
    "CN=Sergeant Foobar,$OU"
    "CN=Random Manager,$OU"
)
$DNs = $users | ?{ $managers -contains $_.Manager } | %{ $_.DistinguishedName }

$DNs | Write-Host

如果你愿意，你可以让它更冗长一点:

$properties = @("Manager")
$managers = @(
    "CN=Colonel Foobar,$OU"
    "CN=Sergeant Foobar,$OU"
    "CN=Random Manager,$OU"
)

$filter = { $managers -eq $_.Manager }
$selector = { $_.DistinguishedName }

$users = Get-ADUser -Filter * -SearchBase $OU -Properties $properties
$DNs = $users | ?{ &$filter } | %{ &$selector }

您听起来好像希望最终拥有多个过滤器。这也很简单:

$properties = @("Manager")
$managers = @(
    "CN=Colonel Foobar,$OU"
    "CN=Sergeant Foobar,$OU"
    "CN=Random Manager,$OU"
)

$filters = @(
    { $managers -contains $_.Manager }
    { ![string]::IsNullOrWhiteSpace($_.DistinguishedName) }
)
$selector = { $_.DistinguishedName }

$users = Get-ADUser -Filter * -SearchBase $OU -Properties $properties
$DNs = $users | ?{ $filters.Invoke() -notcontains $false } | %{ &$selector }