Add xml object to xml file in PowerShell - powershell

Question

I am trying to create an RDCMan file (.rdg xml file) using PowerShell. I have started by defining this template
$newFileTemplate = '<?xml version="1.0" encoding="utf-8"?>
<RDCMan programVersion="2.7" schemaVersion="3">
<file>
<properties>
<expanded>False</expanded>
<name>Office Servers</name>
</properties>
<displaySettings inherit="None">
<liveThumbnailUpdates>True</liveThumbnailUpdates>
<allowThumbnailSessionInteraction>False</allowThumbnailSessionInteraction>
<showDisconnectedThumbnails>True</showDisconnectedThumbnails>
<thumbnailScale>1</thumbnailScale>
<smartSizeDockedWindows>True</smartSizeDockedWindows>
<smartSizeUndockedWindows>False</smartSizeUndockedWindows>
</displaySettings>
</file>
</RDCMan>
'
before creating an xml object like so
$File = 'D:\Test.rdg'
Set-Content $File $newFileTemplate
[XML]$XMLFile = [XML](Get-Content $File)
I would then like to define a function for adding a group of servers
# This function adds a new group element
Function Add-NewGroup($GroupName,$RDCManFile) {
[xml]$GroupXML = #"
<group>
<properties>
<expanded>False</expanded>
<name>$GroupName</name>
</properties>
</group>
"#
$Child = $RDCManFile.ImportNode($GroupXML.group, $true)
$RDCManFile.Configuration.AppendChild($Child)
}
And call it by running
Add-NewGroup('DCs',$XMLFile)
This would allow me to populate the xml file with all of the OUs in AD.
Is anyone able to tell me where I am going wrong?
Thanks
Update: The error I am getting is
You cannot call a method on a null-valued expression.
At D:\Users\user\Desktop\Projects\RDCMan\Create-RDG.ps1:179 char:5
+ $Child = $RDCManFile.ImportNode($GroupXML.group, $true)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (:) [], RuntimeException
+ FullyQualifiedErrorId : InvokeMethodOnNull
You cannot call a method on a null-valued expression.
At D:\Users\user\Desktop\Projects\RDCMan\Create-RDG.ps1:180 char:5
+ $RDCManFile.Configuration.AppendChild($Child)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (:) [], RuntimeException
+ FullyQualifiedErrorId : InvokeMethodOnNull
And I am trying to do what was suggested here https://stackoverflow.com/a/29693625/2165019

Answer 1

The property 'Configuration' cannot be found on this object. Verify that the property exists. error at $RDCManFile.Configuration.AppendChild($Child).
If I can accept a .rdg file format and structure as defined in the Script to create a Remote Desktop Connection Manager group from Active Directory Technet article then I'd use
$RDCManFile.RDCMan.file.AppendChild($Child)
Follow the Theo's answer about calling a function.
Pass parameters as positional
Add-NewGroup 'DCs' $XMLFile
or as named
Add-NewGroup -GroupName 'DCs' -RDCManFile $XMLFile

Answer 2

This error (and second) most likely means that $RDCManFile is null.
You cannot call a method on a null-valued expression.
At D:\Users\user\Desktop\Projects\RDCMan\Create-RDG.ps1:179 char:5
+ $Child = $RDCManFile.ImportNode($GroupXML.group, $true)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (:) [], RuntimeException
+ FullyQualifiedErrorId : InvokeMethodOnNull
Try adding $RDCManFile | Out-Host at the top of the Add-NewGroup function to check what's contained in that variable.

Answer 3

You need to change the way you are calling the function.
Because of the comma in between the parameters, PowerShell sees this as one array value, so only parameter $GroupName will receive something.
Furthermore, you should not use brackets around the params, call the function like this:
Add-NewGroup 'DCs' $XMLFile
or send the parameters using their names:
Add-NewGroup -GroupName 'DCs' -RDCManFile $XMLFile