允许参数接受 Null 或空字符串 PowerShell

Question

在这个方法中，我添加了一个参数 $blindcopy ，我希望在调用时能够密件抄送用户。在不添加该参数的情况下测试此脚本后，一切正常。添加此添加后，我收到一条错误消息 "Cannot validate the argument on parameter 'bcc'. The argument is null or empty" 我已尝试将 AllowEmptyString() 属性添加到参数但仍然没有成功。非常感谢任何帮助！

cls

$BccNull = ""

function SendEmail([string]$BodyString,[string]$SubjectString,[string[]]$EmailRecipientsArray,[string]$FileAttachment=$null,[AllowEmptyString()][string]$BlindCopy)
{ 
    $MethodName = "Send Email"

    # Send the HTML Based Email using the information from the tables I have gathered information in
    try
    {       
        $user = "user@foo.com"
        $pass = ConvertTo-SecureString -String "bar" -AsPlainText -Force
        $cred = New-Object System.Management.Automation.PSCredential $user, $pass

        $SMTPServer = "some.mail.server"
        if([string]::IsNullOrEmpty($BodyString))
        {
            $BodyString = " Body text was empty for user:  $ErrorMessageUserName"
        }


        if([string]::IsNullOrEmpty($FileAttachment)) 
        {
            Send-MailMessage -From "foo@bar.org" -To "bar@foo.org" -Subject $SubjectString -Bcc $BlindCopy -Body $BodyString -BodyAsHtml -Priority High -dno onSuccess, onFailure -SmtpServer $SMTPServer -Credential $cred
        }
        else
        {
            Send-MailMessage -From "foo@bar.org" -To "bar@foo.org" -Subject $SubjectString -Body $BodyString -BodyAsHtml -Attachments $FileAttachment -Priority High -dno onSuccess, onFailure -SmtpServer $SMTPServer -Credential $cred
        }   
    }
    catch
    {
        Write-Host "An Exception has occurred:" -ForegroundColor Red
        Write-Host "Exception Type: $($_.Exception.GetType().FullName)" -ForegroundColor Red
        Write-Host "Exception Message: $($_.Exception.Message)" -ForegroundColor Red 

        #$ErrorMessage =  "Script Error: "+ $_.Exception.Message + "`n" + "Exception Type: $($_.Exception.GetType().FullName)"
        #$SubjectLine = "Script Error:  " + $MethodName + " " + $ErrorMessageUserName

        #SendEmail -BodyString $ErrorMessage -SubjectString $SubjectLine -EmailRecipientsArray $EmailErrorAddress -FileAttachment $null

        $SuccessfulRun = $false
        #ReturnStatusError -CurrentStatus "Error" -ErrorMessage $_.Exception.Message
    }
}

SendEmail -BodyString "Test" -SubjectString "Test" -EmailRecipientArray "foo@bar.org" -FileAttachment $null -BlindCopy $BccNull

Answer 1

即使您函数的 -BlindCopy 参数接受空字符串，Send-MailMessage 的 -Bcc 参数仍然不接受。

我认为对您来说最好的做法是构建参数的哈希表，如果它们不为空则添加可选参数，然后 splat cmdlet 上的哈希表。

function Send-Email {
    Param(
        [Parameter(Mandatory=$true)]
        [string]$BodyString,

        [Parameter(Mandatory=$true)]
        [string]$SubjectString,

        [Parameter(Mandatory=$true)]
        [string[]]$EmailRecipientsArray,

        [Parameter(Mandatory=$false)]
        [string]$FileAttachment = '',

        [Parameter(Mandatory=$false)]
        [AllowEmptyString()]
        [string]$BlindCopy = ''
    )

    try {
        $user = "user@foo.com"
        $pass = ConvertTo-SecureString -String "bar" -AsPlainText -Force
        $cred = New-Object Management.Automation.PSCredential $user, $pass

        $params = @{
            'From'       = 'foo@bar.org'
            'To'         = 'bar@foo.org'
            'Subject'    = $SubjectString
            'Body'       = $BodyString
            'Priority'   = 'High'
            'dno'        = 'onSuccess', 'onFailure'
            'SmtpServer' = 'some.mail.server'
            'Credential' = $cred
        }

        if ($BlindCopy)     { $params['Bcc'] = $BlindCopy }
        if($FileAttachment) { $params['Attachments'] = $FileAttachment }

        Send-MailMessage @params -BodyAsHtml
    } catch {
        ...
    }
}

但即使使用 splatting，我可能仍然不允许参数 -BlindCopy 为空字符串。如果不应将消息密件抄送给某个人，则应完全省略该参数。附件也是如此。如果空字符串显示为 BCC 收件人（或附件），函数应该抛出错误。恕我直言。 YMMV.

允许参数接受 Null 或空字符串 PowerShell

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