#PSTip Mapping the CIM ValueMap and Values qualifiers

Note: This tip requires PowerShell 3.0 or above.

At PowerShell training I did earlier this week, an attendee asked me if there is a way to map a CIM class property’s ValueMap to the Values.

The ValueMap and Values are the CIM property qualifiers. So, when looking at the CIM classes that implement such properties, we need to map the value of the property to a string in the Values qualifier for the property. For example, the Win32_PrinterConfiguration class has a property called Color which defines if the printer is a Monochrome (1) or a Color (2) printer. However, the Color property has the ValueMap and Values qualifiers that define this mapping. When we get an instance of this class using the Get-CimInstance cmdlet, we only see the numbers and not the mapping to string descriptions.

PS> Get-CimInstance -ClassName Win32_PrinterConfiguration | Select Name, Color
Name                                                                Color
----                                                                -----
Snagit 9                                                            2
Send To OneNote 2010                                                2
Microsoft XPS Document Writer                                       2
Fax                                                                 1
DESK                                                                1
Adobe PDF                                                           2
HOME 														   1

Now, if you want to map this to a string value for easy interpretation, you need to create a mapping between the ValueMap and Values qualifiers. I have written a generic function to get the mapping:

Function Get-CimPropertyValueHash {
    [CmdletBinding()]
        Param (
            [Parameter()]
            [String]$Namespace='root\cimv2',
            
            [Parameter(Mandatory=$true)]
            [String]$ClassName,

            [Parameter(Mandatory=$true)]
            [String]$PropertyName
    )

     $CimProperties = Get-CimClass -Namespace $Namespace -ClassName $ClassName | Select -ExpandProperty CimClassProperties -ErrorAction SilentlyContinue

     if ($CimProperties) {
         $CimValueMapProperty = $CimProperties | Where-Object { ($_.Name -eq $PropertyName) -and (($_.Qualifiers -match 'ValueMap') -and ($_.Qualifiers -match 'Values') )}

         if ($CimValueMapProperty) {
              $ValueMapHash = [Ordered]@{}

              $Values = $CimValueMapProperty.Qualifiers["Values"].Value
              $ValueMap = $CimValueMapProperty.Qualifiers["ValueMap"].Value

              for($i = 0; $i -lt $Values.Length; $i++)
              {
                  $ValueMapHash.Add($ValueMap[$i], $Values[$i])
              }
              $ValueMapHash
          } else {
              throw "There is an error retrieving the property details. Either the property does not have the ValueMap and Values qualifiers or the PropertyName is invalid"
          }
 	} else {
      	throw "There is an error retrieving the class details. Please check the Namespace and ClassName values"
 	}
}

It’s very easy to use this function:

PS> Get-CimPropertyValueHash -ClassName Win32_PrinterConfiguration -PropertyName Color
Name                 Value
----                 -----
1                    Monochrome
2                    Color

Once we have the mapping between the ValueMap and Values, we can use the resulting hash to get the string representation of the Color property.

PS> Get-CimInstance -ClassName Win32_PrinterConfiguration | Select Name,@{"Label"="ColorType";Expression={$colorHash[[string]$_.Color]}}
Name                           ColorType
----                           ---------
Snagit 9                       Color
Send To OneNote 2010           Color
Microsoft XPS Document Writer  Color
Fax                            Monochrome
DESK                           Monochrome
Adobe PDF                      Color
HOME                           Monochrome

Now, if you are wondering how to get the CIM class properties with the ValueMap and Values qualifiers, you can use the following code snippet:

Get-CimClass -PipelineVariable Class | Select -ExpandProperty CimClassProperties | Where-Object { $_.Qualifiers -match "ValueMap" -and $_.Qualifiers -match "Values" } | Select @{"Label"="ClassName";Expression={$Class.CimClassName}}, Name