Powershell & XML: Save data to a certain node of xml-file

Question

I have a powershell script which loads data from an xml. The XML looks like:

<meta>
<log>
    <path>D:\logs\l1.log</path>
    <lastwrite>01/30/2015 13:01:00</lastwrite>
    <num>23</num>
</log>
<log>
    <path>D:\log\l2.log</path>
    <lastwrite>02/30/2015 14:02:00</lastwrite>
    <num>67</num>
</log>
</meta>

What I would like to do is to change a certain value in the xml. First I load the Data:

[xml]$xml = Get-Content "D:\config.xml"

My problem is, how can I address a certain log-Node in my xml? What I'm searching for is something like this:

$xml.meta.log.path | where path = "D:\log\l2.log"

And also something to set the new value and save it back to the xml-file.

Maybe sb can help me, I have now idea how to search, but I'm sure there's a way. To use IDs within the log-tags is not a good solution, because I have to address the nodes by the paths.

Martin Brandl · Accepted Answer · 2015-08-03 07:29:46Z

1

You are almost there. Instead of a = use the -eq condition. You also have to use curly brackets and access the current value using $_:

$xml.meta.log.Path | where { $_ -eq 'D:\log\l2.log' }

Alternative, you can use the where path query on $xml.meta.log and select the path in an additional statement:

$xml.meta.log | where path -eq 'D:\log\l2.log' | select -expand path

And here a complete example which modifies the path and save the xml back:

$configPath = 'D:\config.xml'

[xml]$xml = Get-Content $configPath

# Select the log log node where path equals 'D:\log\l2.log' 
$node = $xml.meta.log | where path -eq 'D:\log\l2.log' 

# Set the new path
$node.path = 'D:\newLogPath\newLog.log'

# Save the xml back
$xml.Save($configPath)

edited Aug 3, 2015 at 7:29

answered Aug 3, 2015 at 7:09

Martin Brandl

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2 Comments

Tobi123 Over a year ago

Looks good..but doesn't still work. I get an error message about the line where I set the new path. Error is sth like "The path property was not found within this object. Make sure it is available and determined" Besides, when I want to print the node with "$node.meta.log.path" - nothing appears.

Martin Brandl Over a year ago

hm, the script works fine on my computer. What does $node contain if you print it out?

Tobi123 · Accepted Answer · 2015-08-03 09:21:32Z

1

Ok, I made a little change: XML is now:

<meta>
<log path="D:\logs\l1.log">
    <lastwrite>01/30/2015 13:01:00</lastwrite>
    <num>23</num>
</log>
<log path="D:\log\l2.log">
    <lastwrite>02/30/2015 14:02:00</lastwrite>
    <num>67</num>
</log>
</meta>

And now this code works:

$configPath = 'D:\config.xml'

[xml]$xml = Get-Content $configPath

# Select the log log node where path equals 'D:\log\l2.log' 
$node = $xml.meta.log | where {$_.path -eq 'D:\log\l2.log'}

# Set the new path
$node.line_num = "5"

# Save the xml back
$xml.Save($configPath)

Path is not needed to be modified.

Thanks for your help. Wouldn't have been able to solve this without your code snippet;)

edited Aug 3, 2015 at 9:21

answered Aug 3, 2015 at 8:44

Tobi123

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