Editing XML Attributes using Powershell

Question

So I have an .exe.config file that I am trying to search for a specific attribute within, and then edit it using Powershell Version 4.0 in Windows 7, and I am having issues. I have tried several things, and am not having any success. Here is a trimmed down version of the config file that I am using.

<configuration>
  <Config1>
    <section name="text" type="text, text, text=text" allowLocation="true" allowDefinition="Everywhere" allowExeDefinition="MachineToApplication" restartOnExternalChanges="true" requirePermission="true" />
  </Config1>
  <Config2>
    <module debugLogLevel="Debug" Version="1.0.0.0" />
    <Interested-Item attribute-1="text-text" attribute2="0">
    </Interested-Item>
    <modules>
      <add name="something1" />
      <add name="something2" />
      <add name="something3" />
      <add name="something4" />
      <add name="something5" />
      <add name="something6" />
      <add name="something7" />
    </modules>
  </Config2>        
</configuration>

How would I go about changing the attribute-1 under Interested-Item, using Powershell? Any help would be greatly appreciated.

Here are a few examples of things I have unsuccessfully attempted.

$File = Get-Content $FileLocation
$XML = [XML]$File

foreach ($attribute in $XML.Config2.Interested-Item)
{
     $attribute = Interested-Item.attribute-1 = "Updated Texted"
}
XML.Save($FileLocation)

This does nothing for me. It doesn't edit the File at all.

$File = Get-Content $FileLocation
$node = $File.SelectSingleNode("/Config2/Interetested-Item[@attribute-1]")
$node.Value = "New-Value"
$File.Save($FileLocation)

This returns the following error.

The property 'Value' cannot be found on this object. Verify that the property exists and can be set.At line:5 char:1
+ $node.Value = "New-Value"
+ ~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo          : InvalidOperation: (:) [], RuntimeException
+ FullyQualifiedErrorId : PropertyNotFound

I tried to implement it using -Xpath's from Get-Help Select-XML and was also unsuccessful with that as well.

The only thing that I have had any success with, which won't work in practice is the following.

(Get-Content $FileLocation) | ForEach-Object{$_ -replace "text-*", "NewText"} | Set-Content $FileLocation

This will forcibly work for the first time, and then afterwards won't be able to update the parameter, due to setting a new value. My intention is to run this script multiple times in order to update a group of config files.

Answer 1

There are many ways. For example, you could use XPath:

$File = Get-Content $FileLocation
$XML = [XML]$File

$XPpath = "/configuration/Config2/Interested-Item[@attribute-1]"

# Selecting all nodes that match our $XPath (i.e. all
# '/configuration/Config2/Interested-Item' nodes that have attribute 
# 'attribute-1'.
$nodes = $XML.SelectNodes($XPpath)

# Updating the attribute value for all selected nodes.
$nodes | % { $_.SetAttribute("attribute-1", "foo") }

$XML.OuterXml | Out-File $FileLocation

More info here and generally w3schools.com is your friend when you're dealing with HTML or XML.