Checking input to a Powershell function

Question

I've created a Powershell function that takes in a string. I'm trying to validate that the char count of a string param is over 4, however whenever I check the param, the count is always 1.

Why is this so?

function DeleteSitesWithPrefix($prefix){

    if([string]::IsNullOrEmpty($prefix)){
        Write-Host "Please provide the name of the csv file to use"
        return
    }

    if([string]::$prefix.Length -lt 4){
        Write-Host "Please provide a prefix of 4 or more digits"
        return
    }

Why don't you just use if ($prefix.Length -lt 4) {...?

Ocaso Protal
– Ocaso Protal

2016-03-24 10:43:01 +00:00
Commented Mar 24, 2016 at 10:43 — Ocaso Protal
– Ocaso Protal, Commented Mar 24, 2016 at 10:43

beatcracker · Accepted Answer · 2016-03-24 11:04:14Z

3

Consider rewriting your function using validation attributes:

function DeleteSitesWithPrefix
{
    Param(
        [Parameter(Mandatory = $true)]
        [ValidateScript({$_.Length -ge 4})]
        [ValidateNotNullOrEmpty()]
        [string]$Prefix
    )

    # Do stuff...
}

answered Mar 24, 2016 at 11:04

beatcracker

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1 Comment

Ansgar Wiechers Over a year ago

ValidateNotNullOrEmpty() is redundant, since null/empty values have a (string) length of 0.

Falco Alexander · Accepted Answer · 2016-03-24 10:58:16Z

0

[string]:: means calling a static method of string, but $prefix.Length is not such a method.

this will work:

if($prefix.Length -lt 4){
    Write-Host "Please provide a prefix of 4 or more digits"
    return
}

answered Mar 24, 2016 at 10:58

Falco Alexander

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