Issue modifying XML element value with Powershell

Question

I'm using the following PowerShell to update the value of an element in some XML which works fine, but when I save the XML it appears to change the formatting.

$xmlFileName = "D:\scripts\DbRestoreDIFF.xml"
[xml]$xmlDoc = Get-Content $xmlFileName 
$xmlDoc.TMMsg_CreateTaskReq.taskInfo.subTasks.options.restoreOptions.browseOption.timeRange.toTimeValue = $Timestamp
$xmlDoc.Save($xmlFileName)

After I save the document there are several elements where the format goes from:

<alert>
<alertName></alertName>
</alert>

to:

<alert>
  <alertName>
   </alertName>
</alert>

I've tried preserving whitespace but it didn't seem to help. This is causing me an issue as I'm them unable to pass the XML correctly.

What do you mean with _pass the XML correctly_ ? What issues are cause by this? — Theo
– Theo, Commented May 25, 2020 at 8:07
It isn't read correctly by the application that reads it, which in this instance is Commvault. It assumes there is a value supplied when it is actually blank. — bn25
– bn25, Commented May 25, 2020 at 8:10

vonPryz · Accepted Answer · 2020-05-25 08:32:57Z

1

The default values in XmlDocument's save() are cause for this issue. As described, start and end tags are on different lines:

[xml]$x = '<alert> <alertName></alertName> </alert>'
$x.save([console]::out)
# Output
<?xml version="1.0" encoding="ibm850"?>
<alert>
  <alertName>
  </alertName>
</alert>

To control the output formatting, use an XmlWriter with XmlWriterSettings. An example that saves output to console is like so,

[xml]$x = '<alert> <alertName></alertName> </alert>'
$settings = $(new-object Xml.XmlWriterSettings)
$settings.Indent = $true
$settings.IndentChars = "`t"

$xmlWriter = [Xml.XmlWriter]::create([console]::out, $settings)
$x.save($xmlWriter)
$xmlWriter.close()

# Output
<?xml version="1.0" encoding="ibm850"?>
<alert>
        <alertName></alertName>
</alert>

answered May 25, 2020 at 8:32

vonPryz

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1 Comment

bn25 Over a year ago

Thank you for the help. A variation of the above enabled me to update the XML as expected.

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