TOPIC

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