Sort a PowerShell hash table on a property of the value

Question

I'm having an issue sorting a hash table. I've broken down my code to just bare necessities so as not to overwhelm anyone with my original script.

Write-Host "PowerShell Version = " ([string]$psversiontable.psversion) 
$h = @{}
$Value = @{SortOrder=1;v1=1;}
$h.Add(1, $Value)
$Value = @{SortOrder=2;v1=1;}
$h.Add(2, $Value)
$Value = @{SortOrder=3;v1=1;}
$h.Add(3, $Value)
$Value = @{SortOrder=4;v1=1;}
$h.Add(4, $Value)

Write-Host "Ascending"
foreach($f in $h.GetEnumerator() | Sort-Object Value.SortOrder)
{
    Write-Host $f.Value.SortOrder
}

Write-Host "Descending"
foreach($f in $h.GetEnumerator() | Sort-Object Value.SortOrder -descending)
{
    Write-Host $f.Value.SortOrder
}

The output is

PowerShell Version =  3.0
Ascending
2
1
4
3
Descending
2
1
4
3

I'm sure this is just a simple case of not knowing the correct usage of Sort-Object. The sort works correctly on Sort-Object Name so maybe it has something to do with not knowing how to handle the Value.SortOrder?

Answer 1

Sort-Object accepts a property name or a script block used to sort. Since you're trying to sort on a property of a property, you'll need to use a script block:

Write-Host "Ascending"
$h.GetEnumerator() | 
    Sort-Object { $_.Value.SortOrder } | 
    ForEach-Object {  Write-Host $_.Value.SortOrder }

Write-Host "Descending"
$h.GetEnumerator() |
    Sort-Object { $_.Value.SortOrder } -Descending |
    ForEach-Object { Write-Host $_.Value.SortOrder }

You can filter using the Where-Object cmdlet:

Write-Host "Ascending"
$h.GetEnumerator() | 
    Where-Object { $_.Name -ge 2 } |
    Sort-Object { $_.Value.SortOrder } | 
    ForEach-Object {  Write-Host $_.Value.SortOrder }

You usually want to put Where-Object before any Sort-Object cmdlets, since it makes sorting faster.