当调用仅返回一个对象时，如何强制 Powershell 返回数组? [英] How can I force Powershell to return an array when a call only returns one object?

问题描述

我正在使用 Powershell 在 Web 服务器上设置 IIS 绑定，但在使用以下代码时遇到问题:

I'm using Powershell to set up IIS bindings on a web server, and having a problem with the following code:

$serverIps = gwmi Win32_NetworkAdapterConfiguration 
    | Where { $_.IPAddress } 
    | Select -Expand IPAddress 
    | Where { $_ -like '*.*.*.*' } 
    | Sort

if ($serverIps.length -le 1) {
    Write-Host "You need at least 2 IP addresses for this to work!"
    exit
}

$primaryIp = $serverIps[0]
$secondaryIp = $serverIps[1]

如果服务器上有 2 个以上的 IP，那很好 - Powershell 返回一个数组，我可以查询数组长度并提取第一个和第二个地址就好了.

If there's 2+ IPs on the server, fine - Powershell returns an array, and I can query the array length and extract the first and second addresses just fine.

问题是 - 如果只有一个 IP，Powershell 不会返回单元素数组，而是返回 IP 地址(作为字符串，如192.168.0.100") - 该字符串具有 .length 属性，它大于 1，所以测试通过，我最终得到字符串中的前两个字符，而不是集合中的前两个 IP 地址.

Problem is - if there's only one IP, Powershell doesn't return a one-element array, it returns the IP address (as a string, like "192.168.0.100") - the string has a .length property, it's greater than 1, so the test passes, and I end up with the first two characters in the string, instead of the first two IP addresses in the collection.

如何强制 Powershell 返回单元素集合，或者确定返回的事物"是否是对象而不是集合?

How can I either force Powershell to return a one-element collection, or alternatively determine whether the returned "thing" is an object rather than a collection?

推荐答案

通过以下两种方式之一将变量定义为数组...

将您的管道命令用@ 开头的括号括起来:

Wrap your piped commands in parentheses with an @ at the beginning:

$serverIps = @(gwmi Win32_NetworkAdapterConfiguration 
    | Where { $_.IPAddress } 
    | Select -Expand IPAddress 
    | Where { $_ -like '*.*.*.*' } 
    | Sort)

将变量的数据类型指定为数组:

Specify the data type of the variable as an array:

[array]$serverIps = gwmi Win32_NetworkAdapterConfiguration 
    | Where { $_.IPAddress } 
    | Select -Expand IPAddress 
    | Where { $_ -like '*.*.*.*' } 
    | Sort

或者，检查变量的数据类型...

IF ($ServerIps -isnot [array])
{ <error message> }
ELSE
{ <proceed> }

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