Hiding Properties in Return Results

by Apr 19, 2019

By default, PowerShell shrink-fits most objects and shows only the most important properties by default:

 
PS C:\> Get-WmiObject -Class Win32_BIOS


SMBIOSBIOSVersion : 1.9.0
Manufacturer      : Dell Inc.
Name              : 1.9.0
SerialNumber      : DLGQD72
Version           : DELL   - 1072009
 

To see the real information, users would need to use Select-Object and request all information explicitly:

 
PS C:\> Get-WmiObject -Class Win32_BIOS | Select-Object -Property *


PSComputerName                 : DESKTOP-7AAMJLF
Status                         : OK
Name                           : 1.9.0
Caption                        : 1.9.0
SMBIOSPresent                  : True
__GENUS                        : 2
__CLASS                        : Win32_BIOS
__SUPERCLASS                   : CIM_BIOSElement
__DYNASTY                      : CIM_ManagedSystemElement
__RELPATH                      : Win32_BIOS.Name="1.9.0",SoftwareElementID="1.9.0",SoftwareElementState=3,TargetOperatingSystem=0,Version="DELL   - 1072009"
__PROPERTY_COUNT               : 31
__DERIVATION                   : {CIM_BIOSElement, CIM_SoftwareElement, CIM_LogicalElement, CIM_ManagedSystemElement}
__SERVER                       : DESKTOP-7AAMJLF
__NAMESPACE                    : root\cimv2
__PATH                         : \\DESKTOP-7AAMJLF\root\cimv2:Win32_BIOS.Name="1.9.0",SoftwareElementID="1.9.0",SoftwareElementState=3,TargetOperatingSystem=0,Version="D
                                 ELL   - 1072009"
BiosCharacteristics            : {7, 9, 11, 12...}
BIOSVersion                    : {DELL   - 1072009, 1.9.0, American Megatrends - 5000B}
BuildNumber                    : 
CodeSet                        : 
…
ClassPath                      : \\DESKTOP-7AAMJLF\root\cimv2:Win32_BIOS
Properties                     : {BiosCharacteristics, BIOSVersion, BuildNumber, Caption...}
SystemProperties               : {__GENUS, __CLASS, __SUPERCLASS, __DYNASTY...}
Qualifiers                     : {dynamic, Locale, provider, UUID}
Site                           : 
Container                      : 
 

How can you achieve the same when you write your own PowerShell functions and return your own custom objects?

Simply tell PowerShell the names of the most important properties that should be visible by default. Below is an example. The function Get-Info creates a custom object with five properties. Before the function returns this object, it tags the object with some PowerShell wizardry and lists the default properties:

function Get-Info
{
  
  # prepare the object returned by the function
  $result = [PSCustomObject]@{
    Name = $env:username
    Date = Get-Date
    BIOS = Get-WmiObject -Class Win32_BIOS | Select-Object -ExpandProperty SMBIOSBIOSVersion
    Computername = $env:COMPUTERNAME
    Random = Get-Date
  }
  
  #region Define the VISIBLE properties
  # this is the list of properties visible by default
  [string[]]$visible = 'Name','BIOS','Random'
  $typ = 'DefaultDisplayPropertySet'
  [Management.Automation.PSMemberInfo[]]$info =
  New-Object System.Management.Automation.PSPropertySet($typ,$visible)
  
  # add the information about the visible properties to the return value
  Add-Member -MemberType MemberSet -Name PSStandardMembers -Value $info -InputObject $result
  #endregion


  # return the result object
  return $result
}

This is the result:

 
PS C:\> Get-Info

Name  BIOS  Random             
----  ----  ------             
tobwe 1.9.0 01.04.2019 19:32:44



PS C:\> Get-Info | Select-Object -Property *


Name         : tobwe
Date         : 01.04.2019 19:32:50
BIOS         : 1.9.0
Computername : DESKTOP-7AAMJLF
Random       : 01.04.2019 19:32:50
 

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