PowerShell脚本迁移至流水线遇报错：Expressions are only allowed as the first element of a pipeline

问题背景 #

本地运行正常的PowerShell脚本迁移至流水线后报错，移除报错代码段（用于删除指定文件夹并排除部分目录）后脚本可正常执行。

报错代码段 #

Write-Host "Deleting an old content from $DestinationFolder"
Write-Log -logfile $loglocation -Message "Deleting an old content from $DestinationFolder"

# 创建要排除的文件夹正则表达式
$Exclude = 'Do_not_copy\SI\Tools', 'Do_not_copy\AutomaticTesterTests\Tests\Editing\GUI'  # 可以是单个或多个排除项数组
# 每个项会被转义为正则表达式，并用OR符号'|'连接
$notThese = ($Exclude | ForEach-Object { [Regex]::Escape($_) }) -join '|'
# 要删除的文件夹名称数组（不是完整路径）
$justThese = 'Tools', 'Support', 'Management Console', 'Installer', 'GUI', 'Filer', 'Documentation'

(Get-ChildItem -Path $DestinationFolder -Directory -Recurse -Include $justThese -ErrorAction SilentlyContinue).FullName |
Where-Object { $_ -notmatch $notThese } |
Sort-Object Length -Descending |
Remove-Item -Recurse -Force 
Write-Host "Extract $Latestpackage to $DestinationFolder"
Write-Log -logfile $loglocation -Message "Extract $Latestpackage to $DestinationFolder"
Try {
    $zip = [System.IO.Compression.ZipFile]::ExtractToDirectory((Convert-Path $Latestpackage.PSPath), $DestinationFolder)
}
Catch {
    Write-Host "Unable to extract $Latestpackage to $DestinationFolder"
    exit
} 

报错信息 #

2024-10-22T09:52:05.8787706Z E:\Agt1\Default\06\_w\r25\a\AgileQA\AutomaticScript\GetPatches.ps1 : 在
2024-10-22T09:52:05.8788687Z E:\Agt1\Default\06\_w\r25\a\AgileQA\AutomaticScript\PatchVerification.ps1:4823 字符:88
2024-10-22T09:52:05.8789650Z + ... item will be Regex Escaped and joined together with the OR symbol '|'
2024-10-22T09:52:05.8790219Z +                                                                         ~
2024-10-22T09:52:05.8790759Z 表达式仅允许作为管道的第一个元素。
2024-10-22T09:52:05.8791570Z 在 E:\Agt1\Default\06\_w\r25\a\AgileQA\AutomaticScript\PatchVerification.ps1:4824 字符:85
2024-10-22T09:52:05.8792820Z + ... These = ($Exclude | ForEach-Object { [Regex]::Escape($_) }) -join '|'
2024-10-22T09:52:05.8793423Z +                                                                         ~
2024-10-22T09:52:05.8795106Z 表达式仅允许作为管道的第一个元素。
2024-10-22T09:52:05.8795915Z 在 E:\Agt1\Default\06\_w\r25\a\AgileQA\AutomaticScript\PatchVerification.ps1:4826 字符:27
2024-10-22T09:52:05.8796893Z +             $justThese = 'Tools', 'Support', 'Management Console', 'I ...
2024-10-22T09:52:05.8797421Z +                           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2024-10-22T09:52:05.8798303Z 表达式或语句中出现意外的标记'Tools', 'Support', 'Management'。

修复方案 #

报错源于流水线使用的PowerShell版本（大概率是v2.0或更早）对隐式数组声明和复杂管道表达式的解析支持不足，修改如下：

1. 显式使用@()声明数组，替代隐式数组写法
2. 拆分复杂管道表达式为分步执行，避免语法解析冲突

修改后的代码：

Write-Host "Deleting an old content from $DestinationFolder"
Write-Log -logfile $loglocation -Message "Deleting an old content from $DestinationFolder"

# 创建要排除的文件夹正则表达式
$Exclude = @('Do_not_copy\SI\Tools', 'Do_not_copy\AutomaticTesterTests\Tests\Editing\GUI')  # 显式声明数组
# 每个项会被转义为正则表达式，并用OR符号'|'连接
$escapedExcludes = $Exclude | ForEach-Object { [Regex]::Escape($_) }
$notThese = $escapedExcludes -join '|'
# 要删除的文件夹名称数组（不是完整路径）
$justThese = @('Tools', 'Support', 'Management Console', 'Installer', 'GUI', 'Filer', 'Documentation')

(Get-ChildItem -Path $DestinationFolder -Directory -Recurse -Include $justThese -ErrorAction SilentlyContinue).FullName |
Where-Object { $_ -notmatch $notThese } |
Sort-Object Length -Descending |
Remove-Item -Recurse -Force 
Write-Host "Extract $Latestpackage to $DestinationFolder"
Write-Log -logfile $loglocation -Message "Extract $Latestpackage to $DestinationFolder"
Try {
    $zip = [System.IO.Compression.ZipFile]::ExtractToDirectory((Convert-Path $Latestpackage.PSPath), $DestinationFolder)
}
Catch {
    Write-Host "Unable to extract $Latestpackage to $DestinationFolder"
    exit
} 

修复说明 #

• 显式数组声明@()：旧版PowerShell对隐式用逗号分隔的数组支持不稳定，显式声明能确保语法解析正确
• 拆分管道表达式：将($Exclude | ...) -join '|'拆分为两步赋值，避免旧版本解析复杂嵌套表达式时出现语法错误

内容的提问来源于stack exchange，提问作者Bandit