TOPIC

about_Scripting_ValidateCount

SHORT DESCRIPTION

A brief tutorial on validating parameters by count

LONG DESCRIPTION

Here’s another parameter validation attribute you might want to use in

your PowerShell scripting and functions. If your parameter can take an

array of values, you might want to limit that array to a certain size.

For example, your parameter can take an array of computer names but you

don’t want to process more than 5 for some reason. This is where

[ValidateCount()] comes in to play.

This attribute takes two values, the minimum number of accepted parameter

values and the maximum.

[ValidateCount(1,10)]

[string[]]$Computername

If used, this would mean I would need at least one computername but no

more than 10. You could also set both values the same if you wanted an

exact number:

[ValidateCount(2,2)]

[int[]]$Numbers

Now, I’d have to pass exactly 2 numbers as parameter values. Let’s look

at a more complete example.

#requires -version 2.0

Param (

[Parameter(Position=0,Mandatory=$True)]

[ValidateCount(1,5)]

[string[]]$Name

)

Foreach ($item in $name) {

#display the name in a random color

Write-Host $item -ForegroundColor ([system.consoleColor]::GetValues(

"system.consolecolor") | get-random)

}

This simple script writes each name in a random color, assuming I pass

no more than 5 names.

If I exceed that count, PowerShell will throw a tantrum (I mean exception).

When you use this validation test, be sure your parameter is set to

accept an array of values, e.g. [string[]].

SEE ALSO

about_Functions_Advanced_Parameters

http://jdhitsolutions.com/blog