Prof. Powershell

Get Your PowerShell Object Properties In Order

PowerShell 3 deploys a new type adapter that will have you seeing hash table output in the order you want them to appear.

• By Jeffery Hicks
• 12/11/2012

In PowerShell 2, a common technique for creating a custom object is to create a hash table of property values and then use the hash table with New-Object:

PS C:\> $hash=@{
>> Name="Jeff"
>> Title="Prof. PowerShell"
>> Version=$host.version
>> OS=$(Get-wmiobject win32_operatingsystem).caption
>> }
>>
PS C:\> new-object psobject -Property $hash

Name   Version   Title              OS
----   -------   -----              --
Jeff   2.0       Prof. PowerShell   Microsoft Windows 8 Pro

This works, but notice the output. The property values are not displayed in the order I entered them in the hash table. The problem is that in version 2 hash tables are unordered. There is no predicting what order the values will be displayed. The long way around this problem in version 2 is to create a custom format extension. But that's a lot of work.

In PowerShell 3, we finally have ordered hash tables. You create the hash table the same way, but this time use the [ordered] type adapter:

PS C:\> $hash=[ordered]@{
>> Name="Jeff"
>> Title="Prof. PowerShell"
>> Version=$host.version
>> OS=$(Get-wmiobject win32_operatingsystem).caption
>> }
>>
PS C:\> new-object psobject -prop $hash

Name   Title            Version  OS
----   -----            -------  --
Jeff   Prof. PowerShell  3.0     Microsoft Windows 8 Pro

You must put [ordered] right before the hash table, but notice the result. Now the property names are in the same order.

And that's not all. PowerShell 3 also has another type adapter called [pscustomobject]. Now you can create a custom object without having to resort to the New-Object cmdlet. Use the adapter in front of any hash table to turn it into an object:

PS C:\> [pscustomobject]@{
>> Computername = $(Get-wmiobject win32_operatingsystem).csname
>> OS = $(Get-wmiobject win32_operatingsystem).caption
>> Uptime = (get-date) - ([wmiclass]"").ConvertToDateTime((Get-wmiobject win32_operatingsystem).LastBootUpTime)
>> Make = $(get-wmiobject win32_computersystem).model
>> Manufacturer = $(get-wmiobject win32_computersystem).manufacturer
>> MemoryGB = $(Get-WmiObject win32_computersystem).TotalPhysicalMemory/1GB -as [int]
>> Processes = (Get-Process).Count
>> }
>>

Computername : SERENITY
OS           : Microsoft Windows 8 Pro
Uptime       : 13.08:54:46.1946242
Make         : Qosmio X505
Manufacturer : TOSHIBA
Processes    : 115
MemoryGB     : 8

How easy is that?! If for some reason the hash table isn't ordered, you can combine the type adapters:

[pscustomobject][ordered]@{...

These are great tools that make it even easier to create custom objects from the PowerShell console. In a script, you might still want to use New-Object simply because it is clearer than [pscustomobject]. But I would still use [ordered] when defining the hash table.

So get to PowerShell 3 and get your object properties in order.

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