Properties - Inspect, filter, select, enrich, and sort objects

Everything in PowerShell is already or becomes a .NET object. Therefore, you should be familiar with how to handle and analyze them. Objects are easiest to visualize as text tables, but keep in mind that the entries themselves can also be objects.

• PowerShell modules return objects of a specific type
• external programs return an array of lines Object[] (Array von Textzeilen) zurück.

An understanding of pipelinesis required.

$drives = Get-PSDrive
$files = Get-ChildItem -File

Inspect result object

See object’s type and properties

$drives | Get-Member -MemberType Properties

• in terminals, you may abbreviate with $drives | gm

Count objects

Count elements or file lines

$drives.Count

Add index the each results

$index = 0
$drives | foreach {
    $_ | Add-Member -NotePropertyName "Index" -NotePropertyValue ($index++) -Force
}
$drives | select Index, Name, Root

Narrow down a result

Select specific indexes

$drives | select -Index 2, 4, 7 

$drives[2, 4, 7]
$drives[@(2; 4; 7)]

Select a range at the beginning, end or with specific indexes at the beginning

$drives | select -First 2 -Last 3

$drives[0..1 + -3..-1]
$drives[@(0..1; -3..-1)]

Select duplicates only once

$drives.Provider | select -Unique

Condition expression(s) to be selected

• Learn operators using: Get-Help about_Comparison_Operators

$drives | where {$_.Root -match "^HKEY_"}

$files | where { `
    ( $_.Extension -eq ".xml" -or $_.Name -like "example*" ) `
    -and 
    $_.LastWriteTime -ge [DateTime]::"2000-12-31" `
}

• in terminals, you may abbreviate with $drives | where Name -match "vpn"

Select specific properties of a result

View all properties

$drives | select -Property *

Select existing properties

$drives | select -Property Verb, Noun

Select a precalculated property

$files | foreach { [PSCustomObject]@{
    Name = $_.Name;
    "Size in MB" = [Math]::Round($_.Length / 1MB, 2);
}}

Select a property to be calculated dynamically during readout

$files | select -Property @(
	"Name",
	@{
    	Label = "Size in MB"
    	Expression = { [Math]::Round($_.Length / 1MB, 2) }
    }
)

• in terminals, you may abbreviate with $files | select Name, @{name="Size in MB"; expr={[Math]::Round($_.Length / 1MB, 2)}}

Sort a result

Sort ascending / default direction

$drives | sort -Property Version, Name

Specify sorting direction

$drives | sort -Property Version -Descending

$drives | sort -Property @(
	@{
    	Expression = "Version"
    	Descending = $True
    },
	"Name"
)

• in terminals, you may abbreviate with $drives | sort @{expr="Version"; desc=$True}, Name

---

Sources:

• 2023-03-19: about Calculated Properties - PowerShell | Microsoft Learn
• 2023-03-19: Add a calculated property with Select-Object in PowerShell – 4sysops
• 2023-03-10: Select-Object (Microsoft.PowerShell.Utility) - PowerShell | Microsoft Learn
• 2023-03-10: Add-Member (Microsoft.PowerShell.Utility) - PowerShell | Microsoft Learn
• 2023-03-10: Ultimate Guide to Using PowerShell Add-Member Cmdlet - i Love PowerShell
• 2023-03-10: String.PadRight Methode (System) | Microsoft Learn

Related:

• Compare static and dynamic property calculation

Tags:
PowerShell Objects - Handle, Import, Export, Filter and RegEx query objects