来自PowerShell中参数的自定义错误 [英] Custom error from parameters in PowerShell

问题描述

如果测试失败，例如Test-Path，是否可以让ValidateScript生成自定义错误消息?

Is it possible to have ValidateScript generate a custom error message when a test fails, like say Test-Path?

代替此:

Test-Folder:无法验证参数'Folder'上的参数.参数"blabla"的参数的"Test-Path $ _ -Path Type Container"验证脚本未返回True的结果.确定验证脚本失败的原因，然后再次尝试逗号.

Test-Folder : Cannot validate argument on parameter 'Folder'. The "Test-Path $_ -Path Type Container" validation script for the argument with value "blabla" did not return a result of True. Determine why the validation script failed, and then try the comma and again.

最好在$Error变量中报告它:

找不到文件夹"，也许是网络问题?

The 'Folder' is not found, maybe there are network issues?

代码:

Function Test-Folder {
    Param (
        [parameter(Mandatory=$true)]
        [ValidateScript({Test-Path $_ -PathType Container})]
        [String]$Folder
    )
    Write-Host "The folder is: $Folder"
}

解决方法1:

我可以删除Mandatory=$true并进行如下更改.但这并不能为我提供正确的Get-Help语法，也不会进行Test-Path验证，因为它只会检查参数是否存在.

I could remove the Mandatory=$true and change it as below. But this doesn't give me the correct Get-Help syntax and doesn't do the Test-Path validation, because it only checks if the parameter is present.

Function Test-Folder {
    Param (
        [parameter()]
        [String]$Folder = $(throw "The $_ is not found, maybe there are network issues?")
    )
    Write-Host "The folder is: $Folder"
}

解决方法2:

我在

I found this workaround on a blog post, but the problem is that it generates two errors instead of one.

Function Test-Folder {
    Param (
        [parameter(Mandatory=$true)]
        [ValidateScript({
            if (Test-Path $_ -PathType Container) {$true}
            else {Throw "The $_ is not found, maybe there are network issues?"}})]
        [String]$Folder
    )
    Write-Host "The folder is: $Folder"
}

解决方法3:

我可以也可以尝试通过添加评论部分来使其更加清晰.但是，这仍然不是理想的结果，因为最终用户需要可以读取该错误.

I could also try to make it more clear by adding a comment section. However, this is still not the desired result as the error needs to be readable to end users.

Function Test-Folder {
    Param (
        [parameter(Mandatory=$true)]
        [ValidateScript({
        # The folder is not found, maybe there are network issues?
        Test-Path $_ -PathType Container})]
        [String]$Folder
    )
    Write-Host "The folder is: $Folder"
}

推荐答案

您的ValidateScript应该看起来像这样:

Your ValidateScript should look something like this:

[ValidateScript({
    try {
        $Folder = Get-Item $_ -ErrorAction Stop
    } catch [System.Management.Automation.ItemNotFoundException] {
        Throw [System.Management.Automation.ItemNotFoundException] "${_} Maybe there are network issues?"
    }
    if ($Folder.PSIsContainer) {
        $True
    } else {
        Throw [System.Management.Automation.ValidationMetadataException] "The path '${_}' is not a container."
    }
})]

这会给您这样的消息:

Test-Folder:无法验证参数'Folder'上的参数.不能 找到路径"\\ server \ Temp \ asdf"，因为它不存在.也许有 网络问题?

Test-Folder : Cannot validate argument on parameter 'Folder'. Cannot find path '\\server\Temp\asdf' because it does not exist. Maybe there are network issues?

或者:

Test-Folder:无法验证参数'Folder'上的参数.路径 '\\ server \ Temp \ asdf'不是容器.

Test-Folder : Cannot validate argument on parameter 'Folder'. The path '\\server\Temp\asdf' is not a container.

如果旧版本的PowerShell引发双重错误，则可能需要在函数内部进行测试:

If the older versions of PowerShell are throwing a double error, you may need to test inside the function:

Function Test-Folder {
    Param (
        [parameter(Mandatory=$true)]
        [String]$Folder
    )

    try {
        $Folder = Get-Item $_ -ErrorAction Stop
    } catch [System.Management.Automation.ItemNotFoundException] {
        Throw [System.Management.Automation.ItemNotFoundException] "The '${Folder}' is not found, maybe there are network issues?"
    }

    if (-not $Folder.PSIsContainer) {
        Throw [System.Management.Automation.ApplicationFailedException] "The path '${_}' is not a container."
    }

    Write-Host "The folder is: ${Folder}"
}

我在PowerShell中一直讨厌的部分是试图找出要捕获的错误；该如何解决?没有抓住一切.自从我终于弄清楚了，这是怎么做的:

The part that I always hated in PowerShell was trying to figure out what error to catch; without catching all. Since I finally figure it out, here's how:

PS > Resolve-Path 'asdf'
Resolve-Path : Cannot find path '.\asdf' because it does not exist.
At line:1 char:1
+ Resolve-Path 'asdf'
+ ~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (asdf:String) [Resolve-Path], ItemNotFoundE
   xception
    + FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.Commands.ResolvePathCommand

PS > $Error[0].Exception.GetType().FullName
System.Management.Automation.ItemNotFoundException

这篇关于来自PowerShell中参数的自定义错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！