PowerShell: Foreach for array in Where-Object to verify match on property

Question

Good day, it´s a little hard to explain what I want to do, for that reason I did added code what I´m looking for.

$IDFilterList = @("1" , "2", "3", "4", "5", "6", "7", "8", "9")
   
    if ($file.Name.Contains("SomeStuff")) {
        $ImportendCollection += $Result | 
        Where-Object { ($_.Level -Match 1) -or ($_.Level -Match 2) -or ($_.Level -Match 3) |
        **** Where-Object { foreach ($id in $IDFilterList) {($_.ID -Match $id)}} |
        Group-Object -Property id, LevelDisplayName, LogName -NoElement | 
        Sort-Object -Property count -Descending
    }

I know that this code isn´t correct in the line with the "stars", but it should explain what i want to do. How must this line be look like correctly?

  Where-Object { foreach ($id in $IDFilterList) {($_.ID -Match $id)}} |

Thanks for your help.

You want to test whether $IDFilterList contains the value of $_.ID? — Mathias R. Jessen
– Mathias R. Jessen, Commented Sep 27, 2021 at 15:09
Since we have no clue what the variables $file, $ImportendCollection, $Result etc. are about, this would be very hard to answer. Please edit your question and tell us what it all means — Theo
– Theo, Commented Sep 27, 2021 at 15:10
Looks like you don't actually need -match: Where-Object {$_.Level -in 1,2,3 -and $_.ID -in $IDFilterList } — Mathias R. Jessen
– Mathias R. Jessen, Commented Sep 27, 2021 at 15:11
@MathiasR.Jessen this was perfectly what i was looking for and it works like a charm! How can i flag it as "solution"? — Larry
– Larry, Commented Sep 27, 2021 at 18:20
@Larry That's great! I've posted a proper answer below, click the checkmark on the left of it to accept it :) — Mathias R. Jessen
– Mathias R. Jessen, Commented Sep 27, 2021 at 18:38

Mathias R. Jessen · Accepted Answer · 2021-09-27 19:55:42Z

1

In this particular case you don't actually need to nest Where-Object - since you're looking for exact matches, you might as well use the -contains or -in operators:

... |Where-Object { $_.Level -in 1,2,3 -and $_.ID -in $IDFilterList }
# or
... |Where-Object { 1,2,3 -contains $_.Level -and $IDFilterList -contains $_.ID }

For reference, the .Where() extension method is often a good tool for nesting filter clauses - it works just like Where-Object, but it supports different filtering modes, including it's First mode which provides for "early exit" once a match is found:

... |Where-Object {
        # assign ID property value to local variable
        $ID = $_.ID
        # Test whether any entries in $IDFilterList is a matching pattern for $ID
        $IDFilterList.Where({ $ID -match $_ }, 'First').Count -gt 0
}

edited Sep 27, 2021 at 19:55

answered Sep 27, 2021 at 18:37

Mathias R. Jessen

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1 Comment

Larry Over a year ago

Thank you very much for your input. It looks like to me that powershell is much more similar to C# than i thought. Your post is exactly what i was looking for and works how you expected!

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