compare-object left or right side only

JohnLBevan picture JohnLBevan · Feb 5, 2015 · Viewed 9.1k times · Source

Quick Question

Is there a better (i.e. more efficient / more concise) way to do this?

compare-object $a $b | ?{$_.SideIndicator -eq '<='}

Detail

Compare-Object gives paramenters -excludeDifferent and -includeEqual to allow you to amend which results you get.

  • using both gives you an inner join
  • using just -includeEqual gives you a full outer join
  • using just -excludeDifferent is pointless; as by default equal items are excluded, so it will now exclude everything.

There are no options for -includeLeft, -excludeLeft or similar.

Currently to do a left outer join where the right side is null (i.e. items in the reference object which are not in the difference object) I need to filter the results manually, as per the code above.

Have I missed something / is there a better way?

http://ss64.com/ps/compare-object.html

Answer

Lo&#239;c MICHEL picture Loïc MICHEL · Feb 5, 2015

there is no option like that for that cmdlet, however you could create a filter (in your profile for example) and then use it to filter the result : something like

filter leftside{
param(
        [Parameter(Position=0, Mandatory=$true,ValueFromPipeline = $true)]
        [ValidateNotNullOrEmpty()]
        [PSCustomObject]
        $obj
    )

    $obj|?{$_.sideindicator -eq '<='}

}

usage

compare-object $a $b | leftside