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Pruning log data with powershell throws null object exception using Where-Object

I'm trying to modify a powershell script to prune its log file at then end of its execution.

this works

$prunedContent =  Get-Content -Path $logfile | Where{[DateTime]($_.Substring(0, $_.IndexOf(' '))) -GE $pruneDate}

this throws a null object exception

$prunedContent =  Get-Content -Path $logfile | Where-Object -InputObject [DateTime]($_.Substring(0, $_.IndexOf(' '))) -GE $pruneDate

vs code gives me a warning

'Where' is an alias of 'Where-Object'. Alias can introduce possible problems and make scripts hard to maintain. Please consider changing alias to its full content.

how can I make the Where-Object work?

I've verified in the debugger that Get-Content is returning the entire contents of the log file. Each line of the log file is known to start with the formatted date/time as YYYY-MM-DD HH:MM:SS

Solution

  • The warning you see, AvoidUsingCmdletAliases, is just a PSScriptAnalyzer rule that recommends not using aliases in your scripts. It's simply telling you that:

    $prunedContent = Get-Content -Path $logfile | Where { [DateTime]($_.Substring(0, $_.IndexOf(' '))) -GE $pruneDate }

    Should be:

    $prunedContent = Get-Content -Path $logfile | Where-Object { [DateTime]($_.Substring(0, $_.IndexOf(' '))) -GE $pruneDate }