PowerShell 中的变量数组具有空成员

Question

我有一个 PowerShell 脚本，我想在继续之前确保某些变量具有值。

所以我有以下内容：

$dataRow = $sheet.Cells.Find($country).Row
$serverCol = $sheet.Cells.Find($serverString).Column
$databaseCol = $sheet.Cells.Find($databaseString).Column
$userCol = $sheet.Cells.Find($userString).Column
$passwordCol = $sheet.Cells.Find($passString).Column
$partnerCol = $sheet.Cells.Find($partnerString).Column

#All variables in this array are required. If one is empty - the script cannot continue
$requiredVars = @($dataRow, $serverCol, $databaseCol, $userCol, $passwordCol, $partnerCol)

但是当我像这样遍历数组时：

foreach ($var in $requiredVars)
{
    Write-Host DataRow = ($dataRow -eq $var)
    Write-Host ServerCol = ($serverCol -eq $var)
    Write-Host DatabaseCol = ($databaseCol -eq $var)
    Write-Host UserCol = ($userCol -eq $var)
    Write-Host PasswordCol = ($passwordCol -eq $var)
    Write-Host PartnerCol = ($partnerCol -eq $var)
    if ($var -eq $null)
    {
        [System.Windows.Forms.MessageBox]::Show("No data found for given string!")
        $excel.Quit()
        return
    }
}

我总是得到消息框。我添加了“Write-Host”部分来查看每个变量的值，然后更改它以查看哪个变量为空，但所有变量都包含值，并且您在此处看到的所有检查都返回“False”。

我想知道我做错了什么以及$requiredVars 数组是否只复制值，而不是引用或其他东西。

Answer 1

您可以考虑使用哈希表来存储所有变量，而不是使用单独的变量。
这使得检查单个项目变得更加简单：

# get the data from Excel and store everything in a Hashtable
# to use any of the items, use syntax like $excelData.passwordCol or $excelData['passwordCol']
$excelData = @{
    'dataRow'     = $sheet.Cells.Find($country).Row
    'serverCol'   = $sheet.Cells.Find($serverString).Column
    'databaseCol' = $sheet.Cells.Find($databaseString).Column
    'userCol'     = $sheet.Cells.Find($userString).Column
    'passwordCol' = $sheet.Cells.Find($passString).Column
    'partnerCol'  = $sheet.Cells.Find($partnerString).Column
}

# check all items in the hash. If any item is $null then exit
foreach ($item in $excelData.Keys) {
    # or use: if ($null -eq $excelData[$item])
    if (-not $excelData[$item]) {   
        [System.Windows.Forms.MessageBox]::Show("No data found for item $item!")
        $excel.Quit()

        # IMPORTANT: clean-up used COM objects from memory when done with them
        [System.Runtime.Interopservices.Marshal]::ReleaseComObject($sheet) | Out-Null
        # Your code doesn't show this, but you'll have a $workbook object in there too
        # [System.Runtime.Interopservices.Marshal]::ReleaseComObject($workbook) | Out-Null
        [System.Runtime.Interopservices.Marshal]::ReleaseComObject($excel) | Out-Null
        [System.GC]::Collect()
        [System.GC]::WaitForPendingFinalizers()

        return
    }
}

Answer 2

直接解决您的问题的一种方法是：

$a = "foo"
$b = "bar"
$c = $null

$requiredVariables = $a, $b, $c

# How many total entries in array?
($requiredVariables).Count

# How many of them have a value?
($requiredVariables | Where-Object {$_}).Count

# So one option for a single check would be:
if (($requiredVariables.Count) -ne ($requiredVariables | Where-Object {$_}).Count) {
    Write-Warning "Not all values provided"
}

然而，另一种 [更好的] 方法是将您的代码放入一个包含参数验证的函数

function YourCustomFunction {
    Param (
    [ValidateNotNullOrEmpty()]
    $a
    ,
    [ValidateNotNullOrEmpty()]
    $b
    ,
    [ValidateNotNullOrEmpty()]
    $c
    )

    Process {
        Write-Output "Your function code goes here..."
    }
}

# Call your function with the params
YourCustomFunction -a $a -b $b -c $c

示例输出：

Test-YourCustomFunction：无法验证参数“c”上的参数。参数为 null 或空。提供一个不为 null 或空的参数，并且 然后再次尝试该命令。 在 line:39 char:48