Printing object properties in Powershell

When working in the interactive console if I define a new object and assign some property values to it like this:

$obj = New-Object System.String
$obj | Add-Member NoteProperty SomeProperty "Test"

Then when I type the name of my variable into the interactive window Powershell gives me a summary of the object properties and values:

PS C:\demo> $obj
SomeProperty                                                                                                                                                                                  
------------                                                                                                                                                                                  
Test

I basically want to do just this but from within a function in a script. The function creates an object and sets some property values and I want it to print out a summary of the object values to the Powershell window before returning. I tried using Write-Host within the function:

Write-Host $obj

But this just output the type of the object not the summary:

System.Object

How can I have my function output a summary of the object's property values to the Powershell window?

Try this:

Write-Host ($obj | Format-Table | Out-String)

or

Write-Host ($obj | Format-List | Out-String)

My solution to this problem was to use the $() sub-expression block.

Add-Type -Language CSharp @"
public class Thing{
    public string Name;
}
"@;

$x = New-Object Thing

$x.Name = "Bill"

Write-Output "My name is $($x.Name)"
Write-Output "This won't work right: $x.Name"

Gives:

My name is Bill
This won't work right: Thing.Name

To print out object's properties and values in Powershell. Below examples work well for me.

$pool = Get-Item "IIS:\AppPools.NET v4.5"

$pool | Get-Member

   TypeName: Microsoft.IIs.PowerShell.Framework.ConfigurationElement#system.applicationHost/applicationPools#add

Name                        MemberType            Definition
----                        ----------            ----------
Recycle                     CodeMethod            void Recycle()
Start                       CodeMethod            void Start()
Stop                        CodeMethod            void Stop()
applicationPoolSid          CodeProperty          Microsoft.IIs.PowerShell.Framework.CodeProperty
state                       CodeProperty          Microsoft.IIs.PowerShell.Framework.CodeProperty
ClearLocalData              Method                void ClearLocalData()
Copy                        Method                void Copy(Microsoft.IIs.PowerShell.Framework.ConfigurationElement ...
Delete                      Method                void Delete()
...

$pool | Select-Object -Property * # You can omit -Property

name                        : .NET v4.5
queueLength                 : 1000
autoStart                   : True
enable32BitAppOnWin64       : False
managedRuntimeVersion       : v4.0
managedRuntimeLoader        : webengine4.dll
enableConfigurationOverride : True
managedPipelineMode         : Integrated
CLRConfigFile               :
passAnonymousToken          : True
startMode                   : OnDemand
state                       : Started
applicationPoolSid          : S-1-5-82-271721585-897601226-2024613209-625570482-296978595
processModel                : Microsoft.IIs.PowerShell.Framework.ConfigurationElement
...

Tip #1

Never use Write-Host.

Tip #12

The correct way to output information from a PowerShell cmdlet or function is to create an object that contains your data, and then to write that object to the pipeline by using Write-Output.

-Don Jones: PowerShell Master

Ideally your script would create your objects ($obj = New-Object -TypeName psobject -Property @{'SomeProperty'='Test'}) then just do a Write-Output $objects. You would pipe the output to Format-Table.

PS C:\> Run-MyScript.ps1 | Format-Table

They should really call PowerShell PowerObjectandPipingShell.