about_Scripting_ValidateRange.help.txt
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about_Scripting_ValidateRange SHORT DESCRIPTION A tutorial on verifying if a parameter value falls in a given range. LONG DESCRIPTION You can use this attribute if you want to verify that a given parameter value falls between some range. Typically this is used for numeric values. This attribute is quite easy to use. Here’s a sample script. Param ( [Parameter(Position=0)] [string]$Property="WorkingSet", [Parameter(Position=1,Mandatory=$True, HelpMessage="How many top processes do you want? The maximum is 20.")] [ValidateRange(1,20)] [string]$Count, [ValidateNotNullOrEmpty()] [string]$Computername=$env:computername ) $m="Getting top {0} processes from {1} sorted by {2}" -f $Count,$Computername,$Property Write-Host $m -ForegroundColor Green Get-Process -ComputerName $computername | Sort -Property $property -Descending | Select -first $Count This script gets the top X number of processes from a computer based on a user-specified property. The default property is WorkingSet. The Count property has [ValidateRange()] attribute that dictates that any value must be between 1 and 20. If you enter a value outside of that range, PowerShell will throw an exception and the script will not run. PS C:\Scripts> .\Demo-ValidateRange.ps1 -Count 25 C:\scripts\Demo-ValidateRange.ps1 : Cannot validate argument on parameter 'Count'. The 25 argument is greater than the maximum allowed range of 20. Supply an argument that is less than 20 and then try the command again. At line:1 char:32 + .\Demo-ValidateRange.ps1 -Count <<<< 25 + CategoryInfo : InvalidData: (:) [Demo-ValidateRange.ps1], ParameterBindingValidationException + FullyQualifiedErrorId : ParameterArgumentValidationError,Demo-Valid ateRange.ps1 PS C:\Scripts> .\Demo-ValidateRange.ps1 -Count 3 Getting top 3 processes from SERENITY sorted by WorkingSet Handles NPM(K) PM(K) WS(K) VM(M) CPU(s) Id ProcessName ------- ------ ----- ----- ----- ------ -- ----------- 2288 121 201804 287396 622 1,748.24 7088 chrome 775 111 254700 263620 501 102.31 8104 thunderbird 619 39 254124 261376 472 2,155.51 1152 svchost Of course, you can skip this and add your own validation test within your script if you prefer to handle errors on your own and perhaps a bit more gracefully. Using [ValidateRange()] really only works with numeric values. If you wanted to validate if a datetime value fell within a range, you’ll have to turn to something else. SEE ALSO about_Functions_Advanced_Parameters http://jdhitsolutions.com/blog |