是否有一些技巧AllowEmptyString

Question

我從來沒有能夠獲得AllowEmptyString驗證屬性的工作。

此：

function Get-InputString(
    [parameter(mandatory=$true, position=0)][string][AllowEmptyString]$Str 
) 
{ 
    $Str 
} 

結果在此：

PS C:\> Get-InputString '' 
Unable to find type [AllowEmptyString]: make sure that the assembly containing this type is loaded. 
At line:2 char:71 
+  [parameter(mandatory=$true, position=0)][string][AllowEmptyString] <<<< $Str 
    + CategoryInfo   : InvalidOperation: (AllowEmptyString:String) [], RuntimeException 
    + FullyQualifiedErrorId : TypeNotFound 

Answer 1

你錯過了該屬性的括號。看到http://technet.microsoft.com/en-us/library/dd347600.aspx

function Get-InputString 
{ 
    Param(
     [Parameter(Mandatory=$true, Position=0)] 
     [AllowEmptyString()] 
     [String] 
     $Str 
    ) 

    $Str 
}