CODEWITHSUNDEEP
powershell
Twdeveloper
Twdeveloper

Reputation: 203

How do I compare variable properties in Powershell?

I am looking to do a comparison on two variables $list and $oldList that I generated using Import/Export-Clixml.

Here is the my reference question that I had previously asked. It contains more details if needed.

How should I store a reference variable for continued iteration in Powershell

Since, I tested the following script successfully:

$list = Get-ChildItem C:\localApps\AutomationTest\Loading | where {$_.PSIsContainer}
$list | Export-Clixml C:\LocalApps\AutomationTest\Loading\foldernames.xml
$oldList = Import-Clixml C:\LocalApps\AutomationTest\Loading\foldernames.xml
$oldList

My goal is to compare the $list.LastWriteTime to the $oldList.LastWriteTime and obtain any new directory names that were added to the list since the "oldList" was generated. These new Directory names will then be processed and added to the "oldList"...and so on.

Was thinking maybe something like the following could work? 

Compare-Object -ref $oldList -diff $list 
if ($list.LastWriteTime -gt $oldList.LastWriteTime} 
"Continue....(Load lastest folder names into process)"

Upvotes: 0

Views: 1370

Answers (2)

Matt
Matt

Reputation: 46730

Compare-Object is what you are asking for. Just need to be sure you are doing the correct post processing. If you are just looking for changes that exist in the $list then use the correct side indicator when filtering with Where-Object.

Compare-Object $oldList $list | Where-Object{$_.Sideindicator -eq "=>"} | Select-Object -expandProperty InputObject

That will just return the Directory.Info objects that correspond to folders that didn't exist in the $oldList. Capturing the output from that command is what you are doing to need for your other processing.

After that then just take $list and output that to the location that $oldList came from. Not much to it other than that.

Upvotes: 0

Chris Kuperstein
Chris Kuperstein

Reputation: 678

Here is an example of doing date time checking against the old XML for each folder item that existed previously. It will skip any that weren't in the old list.

Hopefully this gives you a good starting point.

$oldList = Import-Clixml #etc

function Check-Against ([PsObject]$oldList, [string]$path){

    $currentItems = Get-ChildItem $path | ? {$_.PSIsContainer}

    foreach ($oldItem in $oldList){

        $currentItem = $currentItems | ? Name -like ($oldItem.Name)

        if ($currentItem -ne $null){
            $oldWriteTime = $oldItem.LastWriteTime
            $val = $currentItem.LastWriteTime.CompareTo($oldWriteTime)

            if ($val -gt 0){
                # Folder has been changed since then
                # Do your stuff here
            }

            if ($val -eq 0){
                # Folder has not changed
                # Do your stuff here
            }

            if ($val -lt 0){
                # Somehow the folder went back in time or was restored
                # Do your stuff here
            }
        }
    }
}

Upvotes: 1

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