Validation PowerShell两个参数其中一个可以为null，但不能同时为null

我想知道这是否可以在参数级别而不是在代码中完成： 我有两个参数：$School和$Class

Get-Students -School SchooName # Will give me all Students name in all classes in that School
Get-Students -Class ClassName  # Will give me all Students name in that Class across all schools
Get-Students                   # Should return parameter level error. 

我尝试使用以下方法：

function Get-Students{
param(
    [parameter(ParameterSetName="School no null")]
    [ValidateNotNullOrEmpty()]
    [string]$School,
    [parameter(ParameterSetName="School no null")]
    [AllowNull()]
    [string]$Class,
    [parameter(ParameterSetName="Class no null")]
    [AllowNull()]
    [string]$School,
    [parameter(ParameterSetName="Class no null")]
    [ValidateNotNullOrEmpty()]
    [string]$Class
)
}

但它不是这样工作的

希望我解释得对。或者，若并没有任何方法可以仅从代码内部的参数执行此操作

谢谢

---

River

您可以在代码中测试它们，而无需尝试将此检查填充到参数集中

if ($School -eq $null -and $Class -eq $null) {throw "School and Class must not be null together!"}

---

已更新。下面的注释代码段基于本文。允许同时提供

-Class

或

-School

参数或两者

function Get-Students{
param(
    [parameter(Mandatory=$false)][switch]$SomeThing, # any type instead of [switch]
    # ↑↑↑ parameter(s) in all Parameter Sets

    [parameter(Mandatory=$true,  ParameterSetName="School No Null")]
    [parameter(Mandatory=$true,  ParameterSetName="Class And School")]
    [ValidateNotNullOrEmpty()]
    [string]$School,

    [parameter(Mandatory=$true,  ParameterSetName="Class No Null")]
    [parameter(Mandatory=$true,  ParameterSetName="Class And School")]
    [ValidateNotNullOrEmpty()]
    [string]$Class
)
    Write-Host $PsCmdlet.ParameterSetName -ForegroundColor Cyan
    switch ($PsCmdlet.ParameterSetName) 
    { 
        "School No Null"   { "$School/*,$($SomeThing.IsPresent)"; break} 
        "Class No Null"    { "*/$Class,$($SomeThing.IsPresent)";  break}
        "Class And School" { "$School/$Class,$($SomeThing.IsPresent)";  break}
    }
}
Get-Students -Class "A"
Get-Students -School "West" -SomeThing
Get-Students -Class "A" -School "West"

### errors raised:
#   Get-Students
### Parameter set cannot be resolved using the specified named parameters.
### + FullyQualifiedErrorId : AmbiguousParameterSet,Get-Students
#   Get-Students -Class ""
#   Get-Students -School ""
### Cannot validate argument on parameter '…'. The argument is null or empty.
### + FullyQualifiedErrorId : ParameterArgumentValidationError,Get-Students

原始答案（基于PowerShell团队博客上文章的代码片段）不允许同时提供

-Class

和

-School

参数：

function Get-Students{
param(
 [parameter(Mandatory=$true,  ParameterSetName="School No Null")][ValidateNotNullOrEmpty()]
 [parameter(Mandatory=$false, ParameterSetName="Class No Null")] #[AllowNull()]
 [string]$School,

 [parameter(Mandatory=$true,  ParameterSetName="Class No Null")] [ValidateNotNullOrEmpty()]
 [parameter(Mandatory=$false, ParameterSetName="School No Null")]#[AllowNull()]
 [string]$Class
)
    Write-Host $PsCmdlet.ParameterSetName -ForegroundColor Cyan
    switch ($PsCmdlet.ParameterSetName) 
    { 
        "School No Null" { $School; break} 
        "Class No Null"  { $Class;  break}
    }
}

### valid calls:

Get-Students -Class "A"
Get-Students -School "West"

### errors raised:
### Parameter set cannot be resolved using the specified named parameters.
# Get-Students
# Get-Students -Class "A" -School "West"
### The argument is null or empty.
# Get-Students -Class ""
# Get-Students -School ""

---

非常感谢！我认为这是正确的答案！这意味着变量只能出现一次，但参数条件不同！