无法将参数绑定到参数“InputObject”，因为它为空

Question

我有一个 powershell 脚本，可以测量某些页面上的下载时间，但是我收到上面的错误，我不确定我做错了什么

错误是

无法将参数绑定到参数“InputObject”，因为它为空。

function ResponseTime($CommonName,$URL, $environment) 
{ 
    $Times = 5
    $i = 0 
    $TotalResponseTime = 0 
      Write-HOst $URL
    While ($i -lt $Times) { 
        $Request = New-Object System.Net.WebClient 
        $Request.UseDefaultCredentials = $true 
        $Start = Get-Date 
        Write-HOst $URL
        $PageRequest = $Request.DownloadString($URL) 
        $TimeTaken = ((Get-Date) - $Start).TotalMilliseconds 
        $Request.Dispose() 
        $i ++ 
        $TotalResponseTime += $TimeTaken 
    } 

    $AverageResponseTime = $TotalResponseTime / $i 
    Write-Host Request to $CommonName took $AverageResponseTime ms in average -ForegroundColor Green 

    $details = @{            
        Date             = get-date              
        AverageResponseTime     = $AverageResponseTime              
        ResponseTime      = $Destination 
        Environment = $environment
    }                           
    $results += New-Object PSObject -Property $details
    $random = Get-Random -minimum 1 -maximum 30
    Start-Sleep -s $random
} 

#PRODUCTION
ResponseTime -commonname 'app homepage' -URL 'https://url1' -environment 'PRODUCTION'
ResponseTime -commonname 'department homepage' -URL 'https://url2' -environment 'PRODUCTION'

$results | export-csv -Path c:\so.csv -NoTypeInformation

Answer 1

查看您上次的编辑，$results 似乎只是返回 $null（正如您的错误所说）

唯一的行设置$results是$results += New-Object PSObject -Property $details

它不在您的 Export-CSV 调用范围内，并且 - 即使它会，如果未调用此行，$results 也可能为空。

恕我直言，您应该将其设置为例如ArrayList 如下：

$results = New-Object -TypeName System.Collections.ArrayList

并通过

向其中添加项目

$times = ResponseTime -commonname '' #etc
$results.Add($times) | Out-Null

这为您提供了一个 ArrayList - 即使其中没​​有项目 - 也可以轻松转换为 CSV 和其他格式。

Answer 2

@Clijsters 给出了正确答案；即问题是您的 $results 变量的范围。

这个答案只是提供了一点code review 来帮助您处理其他问题......

function Get-ResponseTime { 
    [CmdletBinding()]
    param (
        [Parameter(Mandatory = $true)]
        [string]$CommonName
        ,
        [Parameter(Mandatory = $true)]
        [string]$URL
        , 
        [Parameter(Mandatory = $true)]
        [string]$Environment
        , 
        [Parameter(Mandatory = $false)]
        [int]$Times = 5
    )    
    [System.Int64]$TotalResponseTime = 0 
    [System.Diagnostics.Stopwatch]$stopwatch = New-Object 'System.Diagnostics.Stopwatch'
    Write-Verbose "Processing URL: $URL"
    1..$times | foreach-object {
        [System.Net.WebClient]$Request = New-Object 'System.Net.WebClient' 
        $Request.UseDefaultCredentials = $true 
        Write-Verboset "Call $_ to URL: $URL"
        $stopwatch.Restart()
        $PageRequest = $Request.DownloadString($URL) 
        $stopwatch.Stop()
        $TimeTaken = $stopwatch.Elapsed.TotalMilliseconds 
        $Request.Dispose() 
        $TotalResponseTime += $TimeTaken 
    } 

    $AverageResponseTime = $TotalResponseTime / $Times 
    Write-Verbose "Request to $CommonName took $AverageResponseTime ms on average" 

    $details = @{            
        Date             = get-date              
        AverageResponseTime     = $AverageResponseTime              
        #ResponseTime      = $Destination #this is not declared anywhere / don't know what this field's for
        Environment = $environment
    }                           
    Write-Output (New-Object 'PSObject' -Property $details)
    #do you really want a delay here?  Doesn't make much sense... may make sense to include a delay in the above loop; i.e. to stagger your tests?
    #$random = Get-Random -minimum 1 -maximum 30
    #Start-Sleep -s $random
} 

#PRODUCTION
[PSObject[]]$results = @(
    (Get-ResponseTime -commonname 'app homepage' -URL 'https://url1' -environment 'PRODUCTION' -Verbose)
    ,(Get-ResponseTime -commonname 'department homepage' -URL 'https://url2' -environment 'PRODUCTION' -Verbose)
)
$results | Export-Csv -LiteralPath 'c:\so.csv' -NoTypeInformation

• 使用动词名词函数名（例如Get-Item）。 What is the naming convention for Powershell functions with regard to upper/lower case usage?
• 使用“Cmdlets”（高级功能）代替（基本）Functions；它们基本上是一样的，只是用[Cmdletbinding()]标记。这样做的原因是您获得了对详细输出等功能的支持。 http://www.lazywinadmin.com/2015/03/standard-and-advanced-powershell.html
• 使用秒表对进程计时（您也可以使用measure-command；但measure-command 函数会抑制/消耗任何输出）。 Timing a command's execution in PowerShell
• 让您的 cmdlet 通过Write-Output 将其值输出到管道（或者您可以省略函数名；由于放置一个没有任何处理内容的变量而导致的任何输出将被馈送到管道；即write-object $a 是与仅由 $a 组成的行相同。
• 将输出捕获到函数外部的 $results 变量中，并在那里处理结果。