The Power of PowerShell pipelining

Every now and again I come back to PowerShell, it's useful as a tool, simple, clean and while I can sometimes say its easy to use, many times I smack my head on the desk.  Working in a Windows environment PowerShell scripts make doing many things easier, though it usually takes me some time to work them out.

For example, I am trying to output some results from failures on running SSIS Tasks, but I only really need to know certain statuses, or in most cases just the failures.  Focusing on the failures there can be a lot of them, if something fails at the beginning EVERYTHING runs and can easily fill up the log.  So while a command like:

    $Results = &'C:\Program Files\Microsoft SQL Server\110\DTS\Binn\DTExec.exe' /Project $Path /Package "$File.dtsx"

Can give me a huge result set, do I really need to display a couple of hundred lines of errors to the console, or to the Test Driver?  No.

I wanted to only pull out the error details, I am skipping over the step where I know there are errors here (just to make it easy) and what I want are the details to notify someone that "Hey, something went wrong here!  Here are some examples, want to know more, log in to the box and do some research!!"

So at first I step through everything (that's how I understand where things are working) and first came up with this:

foreach ($_ in $Results)
{
if ($_ -match "Description")
{
$exec_errors += $_
}
}

Now that is way too long.  A lot of white space, plus do I really need to step through that much?  No I don't, thankfully PowerShell makes this easy, since $Results is an array, I can pipeline it and step through it to match only what I want:

    $Results|?{ $_ -match "Description" }

This gets me only the data I want to display, the rest of what you get for the error messages is meaningless to convey the details of what went wrong.  I pipeline the $Results array into ? which is shorthand for the Where-Object and within the curly braces put what it is I was looking before in my if statement, under my foreach.  So now instead of a 3 or so line statement (not quite counting the curly braces there) I have 1 line!  Yes, there can be only 1.

Still I need someplace to put those results:

    $exec_errors = $Results|?{ $_ -match "Description" }

Now, I have an array of just the details I want and using $exec_errors I can output only what I need to communicate:

Write-Output "Errors in execution: "
if ($exec_errors.length -ge 2) {
Write-Output "$exec_errors[0] `n $exec_errors.length - 1"
} else {
Write-Output $exec_errors
}

I will have to see about making a one-liner of the rest later on.