Powershell 作业意外返回“System.Management.Automation.PSObject”对象而不是 System.Object

Question

我运行一个维护 Powershell 脚本，该脚本远程检查 Windows 服务器事件日志中的各种条目，然后采取适当的纠正/警报措施。

该脚本每 5 分钟运行一次，但由于在尝试查询无法访问/无响应的服务器时 Get-WinEvent 调用超时并出现 RPC 不可用错误，该脚本有时会运行过长时间。

为避免此问题，我正在努力将 Get-WinEvent 调用包装在 Jobs 中，以便我可以对它们应用可配置的超时。

对于查找多个事件的 Get-WinEvent 作业，Receive-Job 正确返回包含“System.Diagnostics.Eventing.Reader.EventLogRecord”对象的“System.Object[]”数组。如果只找到一个事件，则 Receive-Job 将返回一个“System.Management.Automation.PSObject”对象。

如果没有与 Job 相关的代码，查找一个事件的 Get-WinEvent 调用会返回一个非数组“System.Diagnostics.Eventing.Reader.EventLogRecord”对象，该对象可以很容易地用数组包装以供下游使用。

任何人都有更好的方法来为远程 Get-WinEvent 调用添加超时或对返回的“System.Management.Automation.PSObject”而不是非数组“System.Diagnostics.Eventing”的解释/修复。 Reader.EventLogRecord' 对象？

函数和一些示例调用如下所示：

Function CollectRemoteEvents($the_server,$event_log,$events_to_find,$event_label,$search_start,$search_timeout,$max_event_count){
    Try{
        $job_info = Start-Job -name GetEvents -scriptblock {param($server,$logname,$eventID,$StartTime,$MaxEvents) Get-WinEvent -ComputerName $server -FilterHashtable @{"logname"=$logname;"id"=$eventID;StartTime=$StartTime} -MaxEvents $MaxEvents} -Arg $the_server,$event_log,$events_to_find,$search_start,$max_event_count

        #if the provided timeout value is greater than 0, use it
        if($search_timeout -gt 0){
            #if the job takes a while, tell it to timeout after ## seconds
            $wait_result = Wait-Job -id $job_info.id -timeout $search_timeout
        }Else{
            #if the timeout was specified as 0, let the job run to completion
            $wait_result = Wait-Job -id $job_info.id
        }
        
        $current_job_state = Get-Job -id ($job_info.id)
        
        #check if the job has completed before time runs out
        if($current_job_state.State -eq "Completed"){
            #capture the job object
            $job = Get-Job -id ($job_info.id)

            #retrieve the output of the job; if the job raises errors, exceptions will be populated into the $joberror variable
            #NOTE: the $ is *intentionally* left out of the 'joberror' variable name in the command below
            $job_result = $job | Receive-Job -ErrorVariable joberror -ErrorAction Stop
            If($joberror -ne "" -And $joberror -ne $null){
                #if joberror is not empty, the job failed; log it
#               write-host "JobError: '$joberror'"  #used for debugging, this would log to file in a production capacity
            }Else{
#               write-host $job_result.gettype()    #used for debugging
                return ,$job_result
            }
        }else{
            #the search timed out
#           write-host "The event log search timed out." #used for debugging, this would log to file in a production capacity
            return $null
        }
    }Catch [Exception]{
        If($_.FullyQualifiedErrorID -eq "NoMatchingEventsFound,Microsoft.PowerShell.Commands.GetWinEventCommand"){
            #No logon timeout events were registered since $search_start
            write-host "$the_server : No $event_label events were found."
            return @()
        }Elseif($_.FullyQualifiedErrorID -eq "ParameterArgumentValidationError,Microsoft.PowerShell.Commands.GetWinEventCommand"){
            #"argument validation error", exit the function with a return value indicating failure
            write-host "$the_server : Event log retrieval failed, can't check for $event_label events (Argument validation error);"
            return $null
        }Elseif($_.FullyQualifiedErrorID -eq "System.Diagnostics.Eventing.Reader.EventLogException,Microsoft.PowerShell.Commands.GetWinEventCommand"){
            #"the RPC server is unavailable", exit the function with a return value indicating failure
            write-host "$the_server : Event log retrieval failed, can't check for $event_label events (RPC server unavailable);"
            return $null
        }Else{
            #if the server logs cannot be retrieved, exit the function with a return value indicating failure
            write-host "$the_server : Event log retrieval failed, can't check for $event_label events (Check access/permissions)($($_.FullyQualifiedErrorID));"
            return $null
        }
    }
}

$server_name = "localhost"
$system_event_ID = @(6013)
$app_event_ID = @(1033)
$timeout_check_timespan = (Get-Date).AddMonths(-2)
$WinEvent_timeout = 10  #how long to let the Job run before timing out

$returns_array = CollectRemoteEvents $server_name 'System' $system_event_ID "Label One" $timeout_check_timespan $WinEvent_timeout 5
$returns_non_array = CollectRemoteEvents $server_name 'Application' $app_event_ID "Label Two" $timeout_check_timespan $WinEvent_timeout 1

write-host ""
write-host $returns_array
write-host $returns_array.count
write-host ""
write-host $returns_non_array
write-host $returns_non_array.count

---

主返回行上的逗号试图强制返回一个数组（参见：Count property of array in PowerShell with pscustomobjects）

我也尝试过实例化一个数组，然后将结果集添加到其中：

$var = @()
$var += $results
return $var

将结果集转换为数组：

return [Array]($results)

并将结果集作为数组的一部分返回：

return @($results)

---

我认为这是一个不同于“Powershell 中的函数返回值”提议的解决方案中涵盖的问题 - 在我的问题中，对象类型的问题在函数返回之前就存在。

出于调试目的取消注释以下行

#               write-host $job_result.gettype()    #used for debugging

导致打印以下输出：

System.Object[]

System.Management.Automation.PSObject

System.Object[] 行由运行 Get-WinEvent 查询以查找多个事件的作业返回。

“System.Management.Automation.PSObject”行由运行 Get-WinEvent 查询以找到单个事件的作业返回

Answer 1

根据 Reddit 用户的建议进行了大量谷歌搜索后，您似乎必须有效地将单对象返回内容双重包装以使其最终成为一个数组：

#this *does not* work
return @(@($job_result))

#This works
return , @($job_result)