Checking if a string is NULL or EMPTY is very common requirement in Powershell script. If we don’t do that we will end up with run time errors if we try to perform some operation on that string variable which is empty or null. So the question now is, how to check it? Well, belo...
IsNotNullOrEmpty如果值是字串,您可以使用靜態字串函式來檢查值是否為 $null 或同時為空字串。PowerShell 複製 if ( -not [string]::IsNullOrEmpty( $value ) ){...} 當我知道實值類型應該是字串時,我經常會使用這個 。當我檢查 $null 時我是一個防禦腳本手。 每當我呼叫函式並將它指派給變數時,我...
functionTest-MrParameterValidation{ [CmdletBinding()]param( [Parameter(Mandatory)] [string[]]$ComputerName)Write-Output$ComputerName} 如果没有指定ComputerName参数,也许要为其指定一个默认值。 问题是,默认值不能与强制性参数一起使用。 取而代之的是使用带有默认值的ValidateNotNullOrEmpty参数验证属性。
ValidateSetAttribute:限制变量的取值集合 ValidateNotNullAttribute 例子 ValidateNotNullOrEmptyAttribute 例子,注意@()为一个空数组。
特性的值HelpMessage不应为空字符串或 null 值,因为这会导致 PowerShell 解释器在执行函数或 cmdlet 时引发错误。 方式 指定HelpMessage属性的值。 示例 错 PowerShell FunctionBadFuncEmptyHelpMessageEmpty {Param( [Parameter(HelpMessage='')] [String]$Param)$Param}FunctionBadFuncEmptyHelpMessage...
Indicates if this PowerShell object is the owner of the runspace or RunspacePool assigned to this object. Runspace Sets an associated Runspace for this PowerShell instance. This can be null in which case a new runspace is created whenever Invoke* method is called. RunspacePool Sets an ...
I disagree. Allowing[NullString]::Valueto propagate without conversion to[string]::emptyis useful when optional string parameters are handled in bulk using eitherValueFromPipelineByPropertyNameor via hashtable splatting. Here is an example using the former demonstrating parameter passing that arises na...
string to System.Management.Automation.ScriptBlock Cannot use Set-Acl properly despite being file owner and being a member of Administrators Group. Cannot validate argument on parameter 'Name'. The argument is null or empty. Provide an argument that is not null or empty, and then try the...
Indicates if this PowerShell object is the owner of the runspace or RunspacePool assigned to this object. Runspace Sets an associated Runspace for this PowerShell instance. This can be null in which case a new runspace is created whenever Invoke* method is called. RunspacePool Sets an assoc...
that the parameter is not null or empty. This is necessary because it has already been defined as an attribute for the Parameter in PowerShell as part of the Stop-Service cmdlet source code.Executing VALIDATION metadata: [System.Management.Automation.ValidateNotNullOrEmptyA...