Count, Sort and Group-By in Powershell - sorting

Question

Are there any cool cmdlets that will help me do the following?
I want something in Powershell that is as simple as doing the same in SQL:
select RootElementName , count(*) from Table
group by RootElementName
order by RootElementName
I'm all XML files in a directory, finding the root element of each XML file.
$DirectoryName = "d:\MyFolder\"
$AllFiles = Get-ChildItem $DirectoryName -Force
foreach ($Filename in $AllFiles)
{
$FQFilename = $DirectoryName + $Filename
[xml]$xmlDoc = Get-Content $FQFilename
$rootElementName = $xmlDoc.SelectSingleNode("/*").Name;
Write-Host $FQFilename $rootElementName
}
Desired Result:
RootName Count
-------- -----
Root1 15
MyRoot 16
SomeRoot 24
I know I could could either create two arrays, or an array of objects, store the root elements in the array, and do the counts all using typical code, was just hoping that this new language might have something built-in that I haven't discovered yet.
Could I pipe the "Write-Host $FQFilename $rootElementName " to something that would behave something to the SQL I referred to above?

Answer 1

You can get groups and counts by using Group-Object like this:
$AllFiles | Group-Object RootElementName | Sort-Object Name | Select-Object Name, Count
In your current example, Write-Host doesn't write an object to the pipeline that we can sort or group. Write-Host only prints text to the screen to show the user something, ex. a script menu.
$DirectoryName = "d:\MyFolder\"
$AllFiles = Get-ChildItem $DirectoryName -Force | ForEach-Object {
#The FullName-property contains the absolute path, so there's no need to join the filename and $directoryname
[xml]$xmlDoc = Get-Content $_.FullName
$rootElementName = $xmlDoc.SelectSingleNode("/*").Name
#Outputing an object that we can group and sort
New-Object -TypeName psobject -Property #{
FileName = $_.FullName
RootElementName = $rootElementName
}
}
$grped = $AllFiles | Group-Object RootElementName | Sort-Object Name | Select-Object Name, Count
I'm creating an object with a FileName-property and the RootElementName so you have it if you need to retrieve the filename+rootelement for a list. If not, we could simplify this to:
$DirectoryName = "d:\MyFolder\"
$AllFiles = Get-ChildItem $DirectoryName -Force | ForEach-Object {
#The FullName-property contains the absolute path, so there's no need to join the filename and $directoryname
[xml]$xmlDoc = Get-Content $_.FullName
#Output rootelementname
$xmlDoc.SelectSingleNode("/*").Name
}
$grped = $AllFiles | Group-Object | Sort-Object Name | Select-Object Name, Count