Hi everybody,

here are some fundamentals to handle XML Files with powershell.

The following commands uses these XML File

<config description="Config file for testing">
    <system description="Document Management">
        <document authorFirstName="Kirk" authorSurname="Author1" date="20130503 01:15:43" description="Document Hammet" index="3">C:\temp\doc0001.txt</document>
        <document authorFirstName="Lars" authorSurname="Author5" date="20130503 10:05:42" description="Document Ulrich" index="4">C:\temp\doc0002.txt</document>
        <document authorFirstName="Cliff" authorSurname="Author5" date="20130612 11:54:33" description="Document Burton"  index="6">C:\temp\doc0051.txt</document>
        <document authorFirstName="Jason" authorSurname="Author2" date="20130806 04:02:41" description="Document Newsted"  index="1">C:\temp\doc0041.txt</document>
        <document authorFirstName="Robert" authorSurname="Smith" date="20131202 07:12:03" description="Document Trujillo"  index="2">C:\temp\doc0012.txt</document>
        <document authorFirstName="James" authorSurname="Smith" date="20130211 09:05:59" description="Document Hetfield"  index="5">C:\temp\doc0003.txt</document>
    </system>
</config>

Creating  a XML File, create a document root, create subelements, add and set attributes, save the file

# Create a new XML File with config root node
[System.XML.XMLDocument]$oXMLDocument=New-Object System.XML.XMLDocument
# New Node
[System.XML.XMLElement]$oXMLRoot=$oXMLDocument.CreateElement("config")
# Append as child to an existing node
$oXMLDocument.appendChild($oXMLRoot)
# Add a Attribute
$oXMLRoot.SetAttribute("description","Config file for testing")
[System.XML.XMLElement]$oXMLSystem=$oXMLRoot.appendChild($oXMLDocument.CreateElement("system"))
$oXMLSystem.SetAttribute("description","Document Management")
# Save File
$oXMLDocument.Save("c:\temp\config.xml")

Loading an existing XML File, read an element, do some XPATH queries

# Loading a XML File
[[xml]]$oXMLDocument=Get-Content -Path "c:\temp\config.xml"
# or
$oXMLDocument=New-Object System.XML.XMLDocument
$oXMLDocument.Load("c:\temp\config.xml")
# Accessing a node/attribute
write-host $oXMLDocument.config.description
# Get all documents from Author "Smith"
$oDocsSmith=$oXMLDocument.selectNodes("config/system/document[@authorSurname=""Smith""]")
# Get all documents from Author "Smith" with date February 2013, XPATH Query relative to document root, http://msdn.microsoft.com/en-US/library/ms256086.aspx
$oDocsSmithFeb13=$oXMLDocument.selectNodes("config/system/document[@authorSurname=""Smith"" and starts-with(@date,""201302"")]")

Here are some examples
Get all Titles from a RSS Feed

[System.Net.WebClient]$oWebClient = New-Object System.Net.WebClient
# Get Proxy from Internet Explorer
oWebClient.proxy=[System.Net.WebProxy]::GetDefaultProxy()
$oRSSFeed=[[xml]]$oWebClient.DownloadString("http://michlstechblog.info/blog/feed/")
$oRSSFeed.rss.channel.item|foreach{write-host $_.title}

Copy a XML Node from one document to another

# Get XML Document Object from String
[[xml]]$oConfig2Merge='<config description="Users">
  <customers>
    <user surname="Campbell" firstname="Wayne">Wayne</user>
    <user surname="Garth" firstname="Algar">Garth</user>
    <user surname="Cheers" firstname="Phil">Phil</user>
  </customers>
</config>'
# Migrate the customers node to our config file defined at the top of the post
# Get the target config Node
$oXMLConfigTarget=$oXMLDocument.selectSingleNode("config")
# Get the Node which is to migrate
$oXMLCustomers=$oConfig2Merge.config.customers
# or
$oXMLCustomers=$oConfig2Merge.selectSingleNode("config/customers")
# Import the Node with the ImportNode Function from System.XML.XMLDocument
$oXMLConfigTarget.appendChild($oXMLDocument.ImportNode($oXMLCustomers,$true))
$oXMLDocument.Save("c:\temp\config.xml")

To be continued…

Michael