Can I use splatting within a Where-Object using PowerShell? - powershell

Question

What I want to find out if I can do, is splatting in a Where-Object clause or something similar. I know you can do this with parameters already.
I am trying to filter out multiple values from one property using -notlike.
I have looked at https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_splatting?view=powershell-5.1 but nothing is mentioned in here.
An example of what I'm currently trying to do:
$allUsers | Where-Object {($_.UserPrincipalName -notlike "Health*") -and ($_.UserPrincipalName -notlike "admin*")}
I am trying to do it this way as there are lots of accounts I want to exclude that contain the the word "admin" in their UPN. Unfortunately there is a long list of what I need to exclude, as I am running through a cleanup process.
I have been suggested to use an array of exclusions and then try using -notcontains or -notin but this has not worked for me, I'm assuming because I need it to be wildcard friendly.

Answer 1

I think it is a lot easier to use the regex -notmatch operator:
# create a regular expression string by combining the keywords with the OR '|' character
$exclude = ('test','admin','health' | ForEach-Object { [regex]::Escape($_) }) -join '|'
# get all users except the users that have any of the keywords in their UserPrincipalName
Get-ADUser -Filter * | Where-Object { $_.UserPrincipalName -notmatch $exclude }

Answer 2

You can do the following to build a dynamic filter by just comma-separating your exclusion strings, which effectively creates an array of strings ($Exclusions).
$Exclusions = 'Health*','admin*'
$FilterArray = $Exclusions | Foreach-Object {
"UserPrincipalName -notlike '$_'"
}
$Filter = #{'Filter' = "{0}" -f ($FilterArray -join " -and ")}
Get-ADUser #Filter

Answer 3

-notin works fine for me, maybe supply a bit more of your data in your question to see what you;re trying to filter out? Is it the wildcards causing an issue?
$listofexclusions = #("userid1","userid2")
Get-ADUser -Filter * | Where-Object { $_.SamAccountName -notin $listofexclusions } | Select Name,SamAccountName | ft
Edit:
If you need wildcards, there are some previous threads about this here

Answer 4

If you're using something like Get-ADUser you can do what other answers have suggested and let the cmdlet filter the results for you using its built in functionality.
However, if you just want to apply a bunch of -like operations to a collection of objects you can write your own Test-LikeAny function as follows:
function Test-LikeAny
{
param( [string] $value, [string[]] $patterns )
foreach( $pattern in $patterns )
{
if( $value -like $pattern )
{
return $true
}
}
return $false
}
and then you can use it like this:
$values = #(
(new-object pscustomobject #{ "Property1" = "...value1..." }),
(new-object pscustomobject #{ "Property1" = "...value2..." }),
(new-object pscustomobject #{ "Property1" = "...value3..." })
)
$patterns = #( "*value1*", "*value2*" )
$values | Where-Object { -not (Test-LikeAny $_.Property1 $patterns) }
which gives:
Name Value
---- -----
Property1 ...value3...