在PowerShell中捕获级联错误 [英] Catching Cascading Errors in PowerShell

问题描述

我正在使用一个包装脚本，该脚本调用一个函数来查询指定服务器内的某些数据库，并将元数据插入到单独服务器上的特定数据库中。我使用$ error.count变量来确定脚本是否成功。我预计会发生一些许可/提取错误，并希望这些错误被捕获和忽略（$ error.count变量没有增加，但作业日志中写有警告）。我可以确认一个权限错误正在发生并且已被正确捕获。 $ error.count变量没有增加，但是从捕获显示了警告，显示了无法访问的数据库。

I'm working with a wrapper script that calls a function which queries some databases inside specified servers and inserts metadata to a specific database on a separate server. I use the $error.count variable to determine if the script was successful or not. I anticipate some permission/extraction errors to happen and want these to be caught and ignored (no increase in the $error.count variable but having a warning written in the job log). I can confirm one permission error is happening and is being properly caught. The $error.count variable is not increased but a warning is printed from the catch showing the database that could not be accessed.

提取/插入功能后出现了我的问题完成运行。在此函数返回到包装脚本后，我立即再次打印了$ error.count变量。这次，它返回1，就好像先前捕获的错误级联到包装脚本中一样。如前所述，我不希望将其包括在错误计数中。我不确定如何或为什么通过此函数增加$ error.count。

My problem occurs after the extraction/insertion function is finished running. Immediately after this function returns to the wrapper script, I have the $error.count variable print again. This time, it returns a 1 as if the error previously caught cascades into the wrapper script. As I mentioned previously, I do not want this to be included in the error count. I'm not sure how or why the $error.count is increased from this function.

我应该使用其他变量来确定脚本是否失败吗？是否有一些根本原因导致$ error.count在出现错误的函数之外增加而在捕获错误后却没有增加？

Should I use a different variable to determine if the script "failed" or not? Is there some underlying reason why the $error.count would increase outside of the function that has the error while not increasing after the error is caught? Any guidance on this issue would be appreciated.

参考代码：
包装函数：

Code for reference: Wrapper function:

$errorCount = $error.count
    Write-Warning ("$errorCount Before function")
    Extraction/Insertion_Function -serverList $serverList -insertionDB $insertionDB -ErrorAction SilentlyContinue
    $errorCount = $error.count
    Write-Warning ("$errorCount After function")
    } catch {
    Write-Error "Error caught by wrapper: $_"
    }

提取/插入功能：

ForEach ($db in $dbList) {
Write-Warning "$errorCount database
.
.
.
    try {
            $totalProperties = Get-ServerDBMetadata -DBConnectionString ($connStr) -DatabaseName $dbName -EA SilentlyContinue 
            } catch {
                Write-Warning "Unable to extract metadata from $dbname in $server"
                }
}

然后，我在循环中打印出错误计数，该循环从每个数据库中提取/插入元数据到插入数据库，以及在每个包含数据库的服务器的循环中：

I then have the error count printing out inside the loop that extracts/inserts the metadata from each database to the insertion database, as well as in the loop for each server that contains the databases:

WARNING: 0 Before function
WARNING: 0 database
.
.
.
WARNING: 0 database
WARNING: Unable to extract metadata from *database* in *server*
WARNING: 0 database
.
.
.
WARNING: 0 database
**WARNING: 1 After function**

错误（权限问题）被捕获在函数内部，但级联到我的包装器脚本。我希望忽略该特定错误，而不是忽略其他更严重的错误（例如无法连接到我要插入元数据的服务器），因此将-EA Ignore放在包装脚本内的驱动程序函数上问题。

The error (permission issue) is caught inside the function but cascades to my wrapper script. I want this particular error to be ignored while NOT ignoring other, more serious errors (like being unable to connect to the server I'm inserting the metadata into) so placing -EA Ignore on the driver function inside the wrapper script is out of the question.

推荐答案

您的主要问题是try-catch无法捕获错误（即使您没有提供所有代码）是您的cmdlet显式调用 -ErrorAction SilentlyContinue 。 Try / Catch块要求使用终止错误，因此对于函数/ cmdlet，您需要更改为 -ErrorAction Stop 才能使try / catch正确处理错误

Your primary problem with the try-catch not catching the error (even though you don't supply all of the code) is that your cmdlet explicitly calls -ErrorAction SilentlyContinue. Try/Catch blocks REQUIRE the use of terminating errors so in the case of your function/cmdlet, you need to change to -ErrorAction Stop for try/catch to appropriately handle an error from that function/cmdlet.

我们需要为代码中看不到的其他任何功能/ cmdlet进行更新。

This needs to be updated for any other function/cmdlet in the code we can't see.

编辑在以下注释中描述：

Edit described in comments below:

 $n = New-Object PSObject -property @{
    'Test1' = ''
    'Test2' = ''
    'Test3' = ''
}

try {
    get-process someprocess -ErrorAction Stop
    $n.Test1 = $true
} catch {
    $n.Test1 = $false
}

try {
    Get-WmiObject win32_computersystem -ErrorAction Stop
    $n.Test2 = $true
} catch {
    $n.Test2 = $false
}

try {
    Get-Content somefile.ext -ErrorAction Stop
    $n.Test3 = $true
} catch {
    $n.Test3 = $false
}


if ($n.Test1 -and $n.Test2 -and $n.Test3) {
    ## All procedures completed successfully -- do something magical
} else {
    ## At least one test procedure failed.
}

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