Modifying .XML files with Powershell

I was asked to help on one application upgrade recently, and it required modifying hundreds of XML-files. All changes were similar, so it was perfect place to do some script automation.

Note, this is not the only way to modify XML-files, this is my way :)

How do I modify XML-files with PowerShell? That's exactly the question that I had in my mind. But first, the XML file that I had. This is not the actual file, but it has same elements so we can use this as an example:

<WEBSETTINGS>
   <Locations>
    <Url value="~/Change/needed.html" />
    <LogDirectory value="\Logs" />
    <NotNeeded value="This we need to remove" />
  </Locations>
  <Settings>
    <Version value="1.0.0" />
    <SmtpServer value="smtp.example.com" />
  </Settings>
</WEBSETTINGS>

Now that we have a XML file, how do we read that with powershell? Like this:

$XML = New-Object -TypeName XML
$XML.Load("C:\XML-example\example.xml")

That will read file C:\XML-example\example.xml to variable called $XML. And now we can browse through XMLwith that variable, like you can see in this screenshot:

Wow, that's easy.

Now let's try to modify our XML. And that's as easy as setting a value to variable, like this:

$XML.WEBSETTINGS.Locations.Url.value = "http://scattereditnotes.blogspot.com"

And that's it, we have changed value of attribute "Url".

Then we add totally new attribute to our XML, it's a little bit more work, but still quite easy. So, let's add attribute called 'NewAttribute' with value 'New Value', and we add that under section 'Settings'. And code to do so:

$NewRow='<NewAttribute value="New Value"/>'
$NewXmlAttribute = $XML.CreateDocumentFragment()
$NewXmlAttribute.InnerXml = $NewRow
$node=$XML.SelectSingleNode('//Settings')
$node.AppendChild($NewXmlAttribute)

Now, let's remove one not needed attribute. Since we know exactly what attribute we want to remove, it's easy:

$RemoveAttribute = $XML.WEBSETTINGS.Locations.NotNeeded
$XML.WEBSETTINGS.Locations.RemoveChild($RemoveAttribute)

So, now we have done following things, we read XML-file to variable, modified value of attribute, added new attribute, and deleted one. Only one thing to do, save it.

$XML.Save("C:\XML-example\example.xml")

Whole code is here:

#Read XML-file to variable
$XML = New-Object -TypeName XML
$XML.Load("C:\XML-example\example.xml")
#Modify Attribute
$XML.WEBSETTINGS.Locations.Url.value = "http://scattereditnotes.blogspot.com"
#Add new attribute to section Settings
$NewRow='<NewAttribute value="New Value"/>'
$NewXmlAttribute = $XML.CreateDocumentFragment()
$NewXmlAttribute.InnerXml = $NewRow
$node=$XML.SelectSingleNode('//Settings')
$node.AppendChild($NewXmlAttribute)
#Remove attribute
$RemoveAttribute = $XML.WEBSETTINGS.Locations.NotNeeded
$XML.WEBSETTINGS.Locations.RemoveChild($RemoveAttribute)
#Save changes back to XML-file
$XML.Save("C:\XML-example\example.xml")

Nice, but, my task was to modify hundreds of .XML-files. Files were in directories under main directory, one file per directory. And I also wanted to make a backup file of all the original files.

And here is the final code:

#Get all directories to variable
$Directories = get-childitem|where {$_.Attributes -eq 'Directory'}|select FullName
#Go through all directories
foreach ($Directory in $Directories)
{
 #Read XML-file to variable
 $XML = New-Object -TypeName XML
 $XML.Load($Directory.FullName+"\example.xml")
 #Create backup of file
 $XML.Save($Directory.FullName+"\example.xml.backup")
 #Modify Attribute
 $XML.WEBSETTINGS.Locations.Url.value = "http://scattereditnotes.blogspot.com"
 #Add new attribute to section Settings
 $NewRow='<NewAttribute value="New Value"/>'
 $NewXmlAttribute = $XML.CreateDocumentFragment()
 $NewXmlAttribute.InnerXml = $NewRow
 $node=$XML.SelectSingleNode('//Settings')
 $node.AppendChild($NewXmlAttribute)
 #Remove attribute
 $RemoveAttribute = $XML.WEBSETTINGS.Locations.NotNeeded
 $XML.WEBSETTINGS.Locations.RemoveChild($RemoveAttribute)
 #Save changes back to XML-file
 $XML.Save($Directory.FullName+"\example.xml")
}

This is what our XML-file looks like after our modification.

<WEBSETTINGS>
  <Locations>
    <Url value="http://scattereditnotes.blogspot.com" />
    <LogDirectory value="\Logs" />
  </Locations>
  <Settings>
    <Version value="1.0.0" />
    <SmtpServer value="smtp.example.com" />
    <NewAttribute value="New Value" />
  </Settings>
</WEBSETTINGS>

And that is so beautiful.